"I don't want to ruin anything,'' he says. "My arm feels great. I'm in the best shape of my life, and there hasn't been a period of time where we haven't been able to do our workouts and progress. The next time I step on the field, it will be with my teammates, and that's a good feeling.''
Nathan, 36, expects to be throwing to live batters when spring training starts next month and return to his familiar role as the anchor of the Minnesota Twins' bulllpen, a year after he had ligament replacement surgery.
"My mindset is to go back to the job I had been doing,'' says Nathan, a four-time All-Star who averaged 41 saves a year from 2004-2009.
Twins general manager Bill Smith said that how Nathan will be used is up to manager Ron Gardenhire, and it's a decision that will be made in spring training.
The Twins used two closers last season in Nathan's absence. Jon Rauch had 21 saves before Minnesota acquired Matt Capps from the Washington Nationals in July. Capps had 16 saves for the Twins.
"It will be nice to have Matt Capps there to close if needed,'' Nathan says. "If I go back-to-back days, I'm not sure how good I'm going to feel on the third day.''
The Twins' bullpen is in a state of flux after losing Rauch to the Toronto Blue Jays, Jesse Crain to the Chicago White Sox and Matt Guerrier to the Los Angeles Dodgers in the free-agent market.
In addition to Capps and lefty Jose Mijares at the back end, the Twins plan to rebuild with pitchers such as Glen Perkins, Pat Neshek, Anthony Slama, Alex Burnett, Jeff Manship, Scott Diamond and Jim Hoey.
Last spring, Nathan felt pain in his right elbow pitching in a Grapefruit League game on March 6. Three weeks later, doctors took a ligament from his left elbow and moved it into his right elbow to replace the torn collateral ligament.
Instead of closing for the Twins in their new Target Field, Nathan spent last season rehabilitating in Minnesota and at the University of Tennessee. (He lives in Knoxville.) Now, as spring training nears, Nathan's workouts are returning to the routine of a normal winter.
His work on the mound started with him throwing 15 pitches at 50 percent effort and has moved up to 30 pitches at 75 percent effort. Nathan might throw a live batting practice session before he leaves for camp in Fort Myers, Fla.
Nathan's velocity isn't where it should be, but he said it is too early to be concerned. He has the itch to get to Florida, but is trying to focus solely on each day of his recovery.
"The biggest thing about rehabilitation is that you can't look ahead,'' Nathan said. "You have to maximize your exercise each day. I'm extremely excited, but you have to realize the time left here is valuable. You can't look for the light at the end of the tunnel. You have to concentrate on the task on hand.''
That approaches works for baseball as well. The Twins have been swept by the New York Yankees in the first round of the playoffs in each of the last two years. Nathan watched from Knoxville when it happened last October. In 2009, he gave up a walk-off home run to Alex Rodriguez in a Game 2 loss.
That one still hurts: "We want to get back, we want to beat the Yankees and advance in the playoffs,'' Nathan says. "We have to walk before we run. We have to get ready in spring training. And, there's plenty to do before I go Florida.''
Nathan isn't the only prominent pitcher looking to bounce back from an injury-marred 2010. Here's a look at how some other top hurlers are progressing on their road to recovery:
Stephen Strasburg and Chien-Ming Wang, Washington Nationals
No injured pitcher will be watched as closely as Strasburg, the 22-year-old who electrified the baseball world with his blazing fastball and knee-buckling breaking pitches after being called up to the majors last summer. Strasburg had ligament replacement surgery on his right elbow last summer, but will likely be throwing soon. That could put him on course for a return in late September.
Strasburg is in San Diego and expects to be throwing when he gets to spring training in Viera, Fla. Last season, after starting at Class AA and AAA, Strasburg was 5-3 with a 2.91 ERA with 92 strikeouts in 68 innings with the Nationals before the injury.
Wang, 30, last pitched for the New York Yankees in 2009. He was supposed to be in the Nationals' rotation last season, but an injured right shoulder kept him out. Wang decided to sign with the Nationals this season to re-pay them for their loyalty from 2009.
The Nationals would like nothing better than for Wang to return to his form of 2006 and 2007, when he had consecutive 19-win seasons for the Yankees. There's encouraging news: Wang pitched in the Instructional League without any problems.
He'll be competing with eight pitchers for a rotation spot. The Nationals say Wang has progressed from rehab to preparation workouts.
Jake Peavy, Chicago White Sox
The White Sox gave up four prospects to get Peavy, a former National League Cy Young Award winner, from the San Diego Padres in 2009 and have been waiting for a stable return on that investment ever since.
They aren't sure how long they'll have to wait. Peavy, who has won just 10 games for the White Sox since the trade, didn't pitch after July because of a shoulder injury that required surgery in September. Even though he's ahead of schedule in his rehabilitation, the White Sox have no timetable for the 30-year-old Peavy's return.
White Sox manager Ozzie Guillen is thinking about using lefty reliever Chris Sale in the rotation while Peavy is out, but pitching coach Don Cooper didn't like the split responsibility, so it appears the top candidate to join Gavin Floyd, Mark Buehrle, Edwin Jackson and John Danks in the rotation is reliever Tony Pena. (Sale could be the White Sox's closer.)
Johan Santana and Chris Young, New York Mets
Santana, a two-time Cy Young winner for the Twins, had surgery on his left shoulder in September and might not return until at least June. In their ace's absence, the Mets hope that the recently-signed Chris Young, another pitcher with a sore shoulder, will be healthy enough to pitch in a rotation that has Mike Pelfrey, R.A. Dickey, Jonathon Niese and Chris Capuano, another newcomer who pitched for the Milwaukee Brewers last season.
Young had shoulder surgery in August of 2009 and, after pitching one game in April for the San Diego Padres, he returned to make three September starts as the Padres contended in the National League West. Young didn't have his usual velocity, but he was effective, allowing just two runs in 14 innings.
When healthy, Young's height -- he's 6-10 -- and delivery make his fastball difficult to hit. He's been durable, too, having made at least 30 starts every season from 2006-08. Mets general manager Sandy Alderson said that if Young, 31, can pitch, that will allow the Mets to keep from rushing prospects.
"Let's face it, you dream on the upside for a veteran coming back from injury,'' Mets general manager Sandy Alderson said. "Chris is certainly not without risk, but we have a lot of faith in him. We believe he's healthy and that our ballpark (Citi Field, where the dimensions are spacious) is the right one for him. We believe he'll be a success.''
Brandon Webb, Texas Rangers
The Rangers failed to sign lefty Cliff Lee, so now they hope that Webb, a former Cy Young winner who hasn't pitched for two years, can boost their rotation.
Webb hasn't pitched since Opening Day 2009 with the Arizona Diamondbacks, but says he'll be ready when the Rangers open camp Feb. 17 in Surprise, Ariz. He had shoulder surgery on Aug. 3, 2009, and the only time he's been on the mound in two years came in September when he pitched three innings in three outings in the Instructional League and showed velocity around 95 mph.
"I feel good where I'm at,'' Webb said at a press conference when he signed with the Rangers. "I feel good about getting the work that I did. I felt comfortable on the mound and each time my velocity got better and my stuff got better.''
The Rangers gave Webb, a 31-year-old sinkerballer, a $3 million contract that could be worth $5 million if he reaches his incentives. Webb won the National League's Cy Young Award in 2006 when he pitched 235 innings and went 16-8 with a 3.10 ERA for Arizona. In 2008, he was a 22-game winner.
Rangers general manager Jon Daniels doesn't want to build expectations for Webb but said that Webb might get better as the season goes on.
Brad Penny, Detroit Tigers
Penny was supposed to be a reclamation project for the St. Louis Cardinals last season, but a back injury in May ended his year after just nine starts, two weeks before Detroit's Armando Galarraga had a perfect game taken away by a missed call by umpire Jim Joyce in early June.
Penny finished the year 3-4 with a 3.23 ERA but he had apparently done enough to warrant a contract from the Detroit Tigers this offseason worth $3 million with another $3 million in incentives. His arrival in the Motor City allowed Tigers GM Dave Dombrowski to trade Galarraga to the Diamondbacks, leaving Detroit with a rotation of Justin Verlander, Max Scherzer, Rick Porcello and Phil Coke.
Penny, 32, is a two-time National League All-Star who pitched for the 2003 World Series champion Florida Marlins. He's won 108 games in 11 seasons, including consecutive 16-win seasons for the Los Angeles Dodgers in 2006 and 2007. But he's struggled in the American League. He had a 5.61 for the Boston Red Sox in 2009 and was traded to the San Francisco Giants at midseason, where he went 4-1 in six starts.
Rich Harden, Oakland Athletics
Harden's name is synonymous with injury comebacks -- he's been on the disabled list nine times in his career -- but the good news, says Oakland's general manager, Billy Beane, is that Harden has never had an injury that's required surgery.
"There's no major surgeries and it's not like he's rehabilitating a rotator cuff,'' Beane says. "He just has injuries that linger.''
At 29, Harden, who was sidelined with a glut injury and shoulder tendinitis last season pitching for the Texas Rangers, will compete for the No. 5 spot against several pitchers, including Josh Outman and Brandon McCarthy.
Harden is returning to the team that drafted him and knows him best. He pitched for Oakland from 2003 to 2008, and scouts said that his stuff was better than any of the Big Three of Tim Hudson, Barry Zito and Mark Mulder.
The Athletics have a strong rotation and a deep bullpen, fueled by the signings of Brian Fuentes and Grant Balfour, and Beane said that the depth will insolate Harden from overwork and injury so "we don't push him to failure.''
Harden, who was open to going to the bullpen, hasn't pitched 150 innings in a season since 2004, when he won 11 games for Oakland and threw 189 2/3 innings. He's got a biting fastball and a nasty slider, and Beane says a healthy Harden, who signed for $1.5 million, could be a big difference for the Athletics.
"When he's healthy, I've seen him dominate,'' Beane says. "As a dominant pitcher, he's in the top three that I have seen in my career.''
Jeff Francis, Kansas City Royals
Francis, trying to come back from surgery on his left shoulder, was looking for an opportunity, and there's no team with more opportunity than the Royals.
The Royals traded their best pitcher, Zack Greinke, to the Milwaukee Brewers, leaving their rotation in an inconsistent flux. Francis and fellow lefty Bruce Chen will help buy time for prospects to develop.
Luke Hochevar, expected to be the No. 1 starter, is good when he's on, but that doesn't happen very often. Kyle Davies had eight wins last season and is inconsistent. Sean O'Sullivan and Vin Mazzaro, acquired from the Oakland Athletics, are unproven.
Francis signed a $2 million contract with the Royals. He won 14 games for the Rockies in his first full season in 2006. His best season came when he won 17 games and pitched the Rockies into the 2007 World Series. He feels good enough to get 30 starts this season.
"My health record the past few years hasn't been great, but I feel good about where I am,'' Francis said at his introductory press conference. "As long as I can go out there and pitch, I feel like they're going to give me that chance.''
Erik Bedard, Seattle Mariners
The Mariners are determined to get something from the always-injured lefty, but this time, they have a pay-as-you-go plan.
After acquiring Bedard from the Baltimore Orioles in 2008, the Mariners paid him $16 million to pitch 164 innings, not exactly the pitcher that won 28 games combined for the Orioles in 2006 and 2007.
This time, Bedard, 31, who missed last season with a shoulder injury, gets a $1 million base and could earn as much as $6.35 million if he reaches 30 starts and 190 innings. His incentives start at 50 innings and eight starts and the more he pitches, the more money he makes. There's also $750,000 in incentives in case they use him in the bullpen.
The Mariners have Felix Hernandez, the American League's Cy Young Award winner, at the top of their rotation, but after that, rotation candidates include unknowns like Jason Vargas, Doug Fister, Michael Pineda, David Pauley and Luke French.