With Jackson addition, Nationals look ready for a run at October

Jackson was the game's best remaining free-agent pitcher -- and, according to SI.com's Joe Sheehan, was the best overall free-agent starter in this offseason's market. Jackson went 35-30 with a 3.96 ERA and 490 strikeouts in 623 innings in the past three seasons that were split among the Tigers (where he was a 2009 All-Star), Diamondbacks, White Sox and Cardinals (where he made seven postseason appearances and four starts in the club's run to a World Series championship last October). He's not an ace, but Washington only needs him to be solid and sturdy in the middle of the rotation.

The Nationals already traded four well-regarded prospects to the A's this offseason for starter Gio Gonzalez (and immediately signed him to a five-year contract with two options). Now adding Jackson for roughly $10 million is a clear indication that the franchise believes it is on the cusp of its first playoff berth -- and at least its first winning record -- since moving to Washington in 2005.

They face a tough division. The Phillies won't win 102 games again but are the favorites to repeat as NL East champs. The Braves missed last year's wild card by only one game and, if their much-ballyhooed pitching prospects develop as planned, ought to be as good or better. The Marlins and Nationals have both made significant offseason improvements. Still, the improved Washington rotation -- with a healthy Stephen Strasburg to go along with Jordan Zimmermann, new additions Gonzalez and Jackson and either John Lannan or Chien-Ming Wang -- ought to keep them ahead of Miami and playing meaningful games in September.

There is a strong correlation between the number of starts made by a club's intended starting rotation and with its winning percentage, as SI.com's Tom Verducci has written. Jackson is nothing if not durable, having made at least 31 starts in five straight seasons.

His addition leaves the Nationals with at least the six aforementioned starters, while roster holdovers Ross Detwiler and Tom Gorzelanny each made at least 25 starts last season. On a conference call with beat writers, Washington general manager Mike Rizzo reportedly said, "We did not acquire Edwin Jackson to trade another starting pitcher."

That's smart. No one gets through seasons with only five starters, and the Nationals' rotation is especially precarious given Wang's injury history, that Strasburg will likely be restricted to about 160 innings and that Zimmermann, who was held to that limit last year, has never greatly exceeded that benchmark in a season. And if the rotation does hold up, a trade can always be revisited at the July 31 deadline.

Rizzo also said on the conference call that Washington believes Jackson had a flaw in his full wind-up that allowed hitters to see the ball particularly well out of his hand, according to the Washington Post.

Indeed, last year Jackson had an anomalous season in which he was far worse with no one on base (when he'd use the full wind-up) than with runners on (when he'd pitch out of the stretch).

In 2011 Jackson allowed a .339 average, .390 on-base percentage and .478 slugging percentage with the bases empty, effectively turning every hitter into someone slightly better than Texas' MVP candidate Michael Young (whose batting line last year was .338/.380/.474).

With at least one runner on base, however, Jackson shut down opponents, allowing a meager .239/.292/.373 batting line, effectively turning hitters into someone slightly worse than A's catcher Kurt Suzuki (.237/.301/.385).

In contrast, the major-league average of all 2011 pitchers was a .251/.312/.396 opponents' batting line with no one on base and a .261/.332/.403 line with at least one runner on. Historically, that has always been the case that pitchers are better with the bases empty than with runners on. Perhaps all Jackson needs to do is change his delivery or even pitch out of the stretch at all times, like many relievers do.

According to CBSSports.com's Jon Heyman, Jackson rejected a three-year contract for $30 million in order to accept this one-year deal with the Nationals. That's rare for a player to turn down the guaranteed length and dollars, but he's going to be a good fit. If he has a strong season in Washington -- where he'll pitch in a pitcher-friendly home park, against the NL's no-DH lineups and potentially in a playoff race -- he'll hit next year's market at 29 when he could still receive a multi-year contract.

Jackson is durable at a time when a premium is typically paid for such things. He's been above league-average for three straight seasons, with a cumulative 108 ERA+ since 2009, suggesting he's been eight percent better than the average when adjusted for league and ballpark. And his Fielding-Independent Pitching -- essentially, his ERA adjusted for his defense and ballpark -- has decreased in each of the past four seasons all the way down to 3.55 in 2011

Complicating matters, however, is that he's in line to compete against a stronger crop of starters next year, when Matt Cain, Cole Hamels and Zack Greinke are all slated to hit the free-agent market.

Five Nationals pitchers made at least 15 starts last season and only one, Zimmermann, averaged better than 90 miles per hour on his fastball. Three of the other four rated between 89 and 90 mph.

That already was a marked improvement over 2010. As I wrote at the time of Strasburg's second career start that season, he "averaged 97.8 mph while the rest of the Nationals' rotation had managed a major-league worst 87.9 mph."

Jackson, meanwhile, has ranked in the top-five in starters' average fastball velocity in each of the past three seasons and was seventh the year before that; for his career he's averaged 94.2 mph. Jackson has been among the game's best at not only throwing hard but sustaining that velocity deep into games.

He joins a rotation that already includes Strasburg (95.8 in five post-Tommy John starts last year and 97.3 in his dozen starts in 2010), Zimmermann (93.4 last year) and Gonzalez (92.8).

Velocity alone doesn't guarantee anything. Jackson, for instance, has never been a big strikeout pitcher, averaging only 6.7 strikeouts per nine innings both last season and for his career. But speed certainly does make it harder on the hitter, whose margin for error in his swing is reduced.