The Indians are 4-12 against left handed starters so far this season. This is the third worst record in the Major Leagues behind the Cubs and Padres who are both in last place in their divisions. Luckily for the Tribe, they have gone 24-13 against right handed starters, allowing them to stay in second place. There has to be some explanation for this discrepancy and I don't think it is a straight down the line reason like, "the Indians lineup is full of left-handed batters and left-handed batters as a rule can't hit left handed pitchers."
So far this season, Indians hitters have batted .214 (last in MLB) against LHP and .272 (6th in MLB) against RHP. The top team in both splits is the Texas Rangers who have somehow managed to bat just one point different (.288 vs RHP, .289 vs LHP) between the two. The Rangers do have quite a few right handed batters on their roster, but three of their strongest hitters, including their MVP centerfielder Josh Hamilton are lefties. Assuming the immediate return of Carlos Santana, the daily lineup for the Indians should look something like this for the near future:
RF Shin-Soo Choo L
2B Jason Kipnis L
SS Asdrubal Cabrera S
C Carlos Santana S
CF Michael Brantley L
1B Casey Kotchman L
DH Shelley Duncan R
LF Johnny Damon L
We already know which side of the plate each batter hits from, but not necessarily how well they do against pitchers of the same or opposite handedness. Whose fault is it the Indians can't score against lefties?
Starting at the top there is an immediate problem. Shin-Soo Choo is hitting LHP at a pace of .143 on the season while he is hitting .339 against RHP. When Choo was at his best back in 2010, he hit .264 against LHP and .319 against RHP. This proves that Choo wasn't always this bad against left-handers, something must have changed. Even last season when he struggled most of the year he hit .269 against LHP and .254 against RHP. Having a lead-off hitter who can't get on base against a third of Major League pitchers is a big part of the problem, but he isn't the whole lineup.
Jason Kipnis also has a serious difference in his splits. He has hit .210 this year against LHP (much better than Choo, but still poor) and has shelled RHP by hitting .323 against them. His slugging splits are also significant at .346 vs LHP and .519 vs RHP, but he still produces against lefties as he leads the team with 2 home runs and 13 RBI against left handers. The verdict on Kipnis is that he isn't really helping the Indians against lefties, but he isn't hurting them eier.
Next in the lineup come the two switch hitters back to back. You would expect them to both hit better against lefties than the rest of the lineup and you would be half right. Asdrubal Cabrera is currently leading the team with a .339 batting average against lefties and Santana is hitting .231. Cabrera is obviously not the problem here. Carlos Santana is an interesting case because while he hits better against right handers, he gets on base more against left handers. This probably has to due with the fact that he has struggled this season, but is more confident against righties, so he swings more freely. Against left handers he is more patient and has drawn far more walks per at bat (13 BB in 52 AB vs LHP, 17 BB in 103 AB vs RHP). Carlos Santana is a problem, but not the left handed exclusive problem we are looking for.
Michael Brantley is proof that you don't have to be right handed to hit left handers well. Brantley is second on the team with a .296 average against LHP and has 6 extrabase hits against them as well with 12 more against RHP. All his line stats drop slightly against RHP, but he is pretty even across the board. It's not his fault.
With Jack Hannahan's injury, he has two replacements at third. Jose Lopez is hitting .267 vs LHP, good for third on the team and Chisenhall has gone 0-5 so far. Neither player has been starting long enough to draw any real conclusions, but it is safe to say that Lopez is playing way over his head right now and can't be to blame for any poor Indians offense.
Of the bottom three hitters, Kotchman is hitting .160 against LHP while Damon and Duncan are doing slightly better at .231 and .245. Both Duncan and Damon are significantly worse against RHP while Kotchman is slightly better. This part of the lineup hasn't been responsible for much of the run scoring this season so they wind up being slightly insignificant.
The answer to the Indians problems against left handers is the top of the lineup. While some of the problems occurred while Travis Hafner was still playing (.150 vs LHP), he will not be part of this team for the next month, so they will have to move on without him. Choo is the main player at fault at this point and it would probably be beneficial for the Indians to move him down in the lineup and place Brantley in the lead off spot against left handers. As for the rest of the problem it seems to be mostly from the fact that the Indians are hitting better against right handers than expected. No one can expect a lineup with Johnny Damon, Shelley Duncan, Jose Lopez and Casey Kotchman in it to out hit anybody, especially the way they are playing this season. What is keeping the Indians up against righties is the fact that Jason Kipnis, Shin-Soo Choo and for a time Hafner and Hannahan are tearing the cover off the ball against them. This success has made the bottom half of the lineup, which hasn't been able to produce against anyone less important against right handers.
In general along with a lineup change, the Indians are just going to play more small ball against left handers. They should learn from Carlos Santana and be more patient at the plate and not waste at bats. Choo and Damon could also benefit from using the opposite field a little more. Manny Acta could also help his team out a bit by continuing to use Lopez against lefties and possibly adding in Matt LaPorta's bat to give the Indians another look from the right side.