Second-half X-factors who could decide playoff chases

As we wrap up the first half of the 2010 season, there are 17 teams with winning records and 16 of them are within five games of first place in their division. Every division but the NL Central and AL West has more than two teams in the mix. As is always the case, injuries, players returning from injuries, and trades are likely to tip the balance in how the pennant races shake out. Superstars, of course, will play their parts in determining which teams make it to October, but an equally substantial role will be played by these X-factors.

Joba Chamberlain, RHP, Yankees

On Tuesday night, Mariano Rivera announced that he's going to skip the All-Star Game due to some minor injuries. Rivera has been pitching through the pain and doesn't expect to go on the disabled list, but he's unable to pitch more than one inning per appearance, and Yankee manager Joe Girardi has to be extra careful with the 40-year-old's workload. That means Chamberlain, whose frustrating inconsistency has followed him back to the bullpen, will not only have to get out of his own jams, but could be called upon to close at points in the second half (he has already picked up two saves in the first half). While Rivera has been his usual dominant self thus far, the rest of the Yankee pen has been struggling, hurt, or both (see: Park, Chan Ho) for much of the season. Chamberlain dominated out of the pen before the Yankees moved him into the rotation in mid 2008 (1.32 ERA, 12.1 K/9 in 47 2/3 IP). In an AL East race in which the three best teams in baseball are separated by just three games and at least one will miss the playoffs entirely, Chamberlain needs to find that old consistency and fast to help ensure that the reigning world champions will be back in the playoffs to defend their title.

Dayan Viciedo, 3B, White Sox

The White Sox have thrust themselves into the thick of the AL Central race by winning 20 of their last 25 games and are now just one game out of first. They have the pitching depth to stay there, but their offense has been burdened by dismal performances from second base, left field, and third base. With busted prospect Brent Lillibridge and what's left of Andruw Jones the in-house alternatives to incumbents Gordon Beckham and Juan Pierre at the first two positions, 21-year-old Cuban rookie Viciedo stands as the team's best chance at a meaningful and lasting upgrade. Viciedo won't draw many walks, but he has some serious pop and was hitting .290/.329/.525 with 14 homers for Triple-A Charlotte before making his big-league debut two weeks ago. Of the other three men to start at the hot corner for the White Sox, Mark Teahen is hurt, overrated, and capable of moving to left field or perhaps even second base, Jayson Nix was waived, and 43-year-old Omar Vizquel hasn't hit since he was in his thirties. If Viciedo can make a positive contribution to the Pale Hose cause, it would increase the pressure on the second-place Twins and first-place Tigers significantly.

Tommy Hunter, RHP, Rangers

The Rangers have the biggest division lead in baseball (4 1/2 games) and are the only team in their short-stack of a division with a positive run differential. They also have the third-best offense in baseball according to runs scored per game, so if there's a crucial element to the Rangers' ability to hold the lead in their division, it's their pitching, specifically their starting rotation, which has thus far been anchored by a converted reliever and an American who spent the last two years pitching in Japan. C.J. Wilson and Colby Lewis have been sharp, but Wilson is entering unfamiliar territory in terms of total innings, 2009 17-game winner Scott Feldman has been awful, and big off-season addition Rich Harden is back on the disabled list after struggling early on. That puts the pressure on 23-year-old sophomore Tommy Hunter, who returned from an oblique strain in early June and has been impressive in six starts since (5-0, 1.98 ERA). Hunter isn't nearly that good and faded badly down the stretch last year (5.91 ERA in his last 10 starts, including 6.54 in his last six), but if he can settle in around league-average, eat innings, and keep the emergency/spot starters away, he'll help stabilize both the rotation and the team, increasing the Rangers' chances of making their first postseason appearance since 1999.

Martin Prado, 2B, Braves

The NL batting leader is now an NL All-Star, so he's hardly a secret, but Prado still feels like Atlanta's secret weapon. In his first year as the Braves' starting second baseman, the 26-year-old Prado is igniting the Braves' offense with a .332/.372/.482 line, including a .354/.387/.531 performance in 48 games as the team's leadoff hitter since taking over that spot in the lineup in mid-May. Prado's batting average is propping up his on-base percentage, but that doesn't change the fact that he's been on base constantly for the meat of the Braves lineup. When Jason Heyward was batting second, it was Prado he was driving in, and if Heyward has a big second half after resting his injured thumb, it will be in part because Prado continues to get on base for him. Of course, Prado can rake a little himself. He's on pace for 48 doubles and 16 homers, not to mention 72 RBIs and 114 runs, and was a .451 career slugger coming into this season. The degree to which Prado is able to sustain his first-half breakout will be reflected directly in the Braves' ability to hold on to their unexpected division lead.

Johnny Cueto, RHP, Reds

The underdog Reds rode the NL's best offense to the top of the NL Central standings in the first half, but, much like the Rangers, they'll need their pitching to help fortify their position in the second half. Thus far, Cueto and rookie Mike Leake have led the way in the rotation, but Leake is a first-year professional who threw just 142 innings as a college junior last year and this year is pitching on an innings limit believed to be around 170, which would leave him less than 70 innings in his season. Edinson Volquez, who is coming off Tommy John surgery, is looking sharp in Triple-A and could help pick up Leake's slack in the second half, but pitchers in their first year back from that procedure are notoriously shaky. Cuban defector and big-money free-agent signing Aroldis Chapman has been wild in Triple-A and was recently moved to the bullpen. Aaron Harang just hit the DL. Bronson Arroyo is a reliable innings eater, but little more. That puts the onus on Cueto to continue as the staff ace. Given Dusty Baker's predilection for riding his starters in a pennant race and Cueto's small stature (5-foot-10, 185 pounds) and history of arm aches, that could spell trouble for a Reds team looking for the franchise's first postseason berth since 1995.

Chase Headley, 3B, Padres

I've stopped waiting for the Padres to come back to earth. They're not merely leading the NL West, they have the best record in the National League and are tied with the Rangers for the third-best record in baseball entering Wednesday's action. Sure, their offense is pathetic, but their pitching, particularly their bullpen, has been so strong that their Pythagorean record (based on run differential) is still four games better than the next-best team in the division (the similarly pitching-dependent, fourth-place Giants) and the third best in baseball behind the Yankees and Rays. So, just imagine what the Padres could do if someone other than Adrian Gonzalez started hitting. The most likely candidate is Headley, the one other member of the Padres lineup who is actually supposed to be able to hit. A .263/.340/.400 career hitter entering the year and a former second-round draft pick finally returned to his natural position from left field with Kevin Kouzmanoff in Oakland, Headley was hitting .331/.377/.432 on May 8, but slumped badly until late June, when he picked it back up, hitting .327/.414/.423 over his last 13 games. That combination of average and on-base skills reflects what Headley showed in the minors and is well suited to his power-sapping home ballpark, and as a switch-hitter who has added high-percentage basestealing to his repertoire (he has stolen a career-best 11 bases already this year in just 14 attempts), Headley profiles as the Padres' best offensive weapon after Gonzalez. If he can deliver on that promise, he could help keep the surprising Padres in the NL playoff picture.