Just what is Chad Kuhl's ceiling?

Chad Kuhl has been an MLB starting pitcher for almost a full year now. In that time, he's proven that he can be a decent back-end rotation starter. However, there are many times where you watch him and have to wonder if he has what it takes to remain a major league caliber starting pitcher. 

The main thing people point to are his splits against the lefties as opposed to righties. This season so far, Chad Kuhl has compiled quite a discrepancy. Lefties get on base at a .493 clip against him with a wOBA of .498 and lefties have gotten much more production in every area so far against Kuhl. Righties, on the other hand, only get on-base at a .264 clip and have an even lower wOBA against him at .217. The production from righties is also much lower than that of lefties. And this isn't a new thing for Chad Kuhl; you can go through his minor league career and see that lefties historically hit better off of him. 

But what is the reason lefties hit better off of him? Well, the main reason to be offered is the lack of an out pitch against lefties, most notably a lack of a reliable changeup. The changeup can be a crucial pitch for pitchers, and a lot of pitchers need it in their repertoire to get to the next level. Kuhl has a changeup, but it has yet to be super effective for him to this point. 

So far, you look at Chad Kuhl's numbers, and they don't look bad for a 5th starter. Most 5th starters around the league are very meh, and maybe Chad Kuhl is no different. However, you look at his splits against left-handed hitters, and you get very worried because a team can just stack the deck against Kuhl with mostly lefty batters if they have some. This was a similar issue that Juan Nicasio faced in his career before his move to the bullpen, where he's been mostly a mainstay. 

In any case, Chad Kuhl has a ceiling of a backend rotation starter, and he would be a better 5th starter than most. However, you can't help but wonder if his specific talents wouldn't be best utilized out of the bullpen, similar to Nicasio. I'm a big believer in Chad Kuhl, even whilst I have my skepticisms about whether he's an actual MLB-caliber starting pitcher. It all boils down to his changeup. If he masters it, he can be a 3 or 4 starter potentially; if not, he's going to prompt a move to the bullpen eventually.