By Ian Walton
With Kyle Lohse set to return to the St. Louis rotation this Sunday afternoon, the Cardinals will soon be faced with a decision over who will remain as their number five starter. It will likely boil down to who they believe will do the least amount of damage, as Todd Wellemeyer currently sits with a 7-7 record and a 5.58 ERA in 100 innings pitched while Brad Thompson has tallied a 2-6 record and a 5.31 ERA in just shy of 58 innings.
Wellemeyer has fallen hard this season after posting a very respectable 13-9 record with a 3.71 ERA and a 1.25 WHIP in 191.7 IP in 2008. It seems fairly clear that he has become overexposed against left-handed batters, giving up 11 HR, 27 BB, and a 1.98 WHIP along with 28 strikeouts in 48 IP this season. Conversely, he has only yielded 2 HR and 18 walks with a 1.44 WHIP and 36 K in 52 IP against right-handed batters. In 2008, he recorded only 29% of his outs against LHB while in 2009, he has been forced to record 48% of his outs against lefties.
His reliance upon his changeup has thus jumped from 10.8% to 13.1% this season while his slider usage has dropped from 23.7% to 21.4%. This is a big problem, as FanGraphs indicates that he gives up 6.12 runs more than average per 100 changeups thrown compared to giving up 1.87 runs fewer than average per 100 sliders and 1.86 runs fewer than average per 100 curves. In short, teams have realized that his changeup is an inadequate off-speed offering and are stacking their lineups with left-handed hitting in order to compensate.
Thompson joined the 2009 rotation on June 2, making eight starts since. In five of those outings, he failed to last longer than five innings. Much like Wellemeyer, Thompson has been forced to face many more left-handers than in the past, as he has recorded almost exactly as many outs against RHB than LHB this season. This has naturally resulted in him throwing his changeup significantly more often – he has used it a solid 20% of the time following a steady 13% usage in 2007 and 2008.
Unfortunately for Brad, his already poor fastball velocity has dropped from 88 MPH to 87 MPH this season while his changeup velocity has risen from 81 MPH to 83 MPH. A four MPH difference likely won’t fool very many major league batters. To date, his changeup has actually been his most effective offering according to FanGraphs, as his curveball has fared worse. In 29 IP against RHB, Thompson has 9 K against 6 BB with a 1.40 WHIP and 3 HR while in 28 2/3 IP against LHP, Thompson has 13 K against 11 BB with a 1.38 WHIP and 4 HR. Clearly, there isn’t a strong platoon advantage either way.
As counter-intuitive as it may seem, I believe that Brad Thompson may be the Cardinals’ best choice to stay in the rotation while Todd Wellemeyer is best suited as a situational or long relief pitcher out of the bullpen. Wellemeyer’s 5.6 IP per start isn’t protecting the bullpen significantly more than Thompson’s 5.4 IP per start, and Thompson at least appears to have some hope at stopping left-handed batting.
There is some hope, as Wellemeyer has begun to throw a cutter a mere 2.2% of the time this season, and it has fared well in limited action. Ryan Franklin has become as much more effective pitcher against LHB this season due to a sudden 26.2% usage of the cutter (compared to 2.5% last season) in addition to phasing out his slider.
In 2009, Franklin has thrown nine strikeouts against four walks with a 0.77 WHIP in 15 2/3 IP against left-handed batters compared to 15 strikeouts against three walks with a 0.87 WHIP in 17 1/3 IP against right-handed batters. Compare this to Franklin’s 2008 season, when he surrendered a 1.61 WHIP and 21 K:17 BB against LHB while giving up a 1.38 WHIP and 30 K:13 BB against RHB.
If Cardinals pitching coach Dave Duncan could help teach Wellemeyer an effective off-speed option against left-handed pitchers like he did Franklin, then Todd would be versatile enough to return to the starting rotation. Until then, Brad Thompson would be my choice.
Thanks to FanGraphs and their PitchFX data for pitch usage, speeds, and effectiveness.