The Mike Pelfrey experiment is reaching critical mass

When the Detroit Tigers inked Mike Pelfrey to a two-year deal this offseason, a lot of people weren't thrilled. The Tigers saw reason to believe in Pelfrey's decent 2015 campaign. Unfortunately, it's really not working out well. The Tigers have plenty of reasons to try and make this work, but the starting rotation is the team's clear weakness in 2016. And the Tigers can't wait on Pelfrey much longer.

The struggles of the Tigers' rotation have already been well documented. While the Tigers got some tentatively positive news on Jordan Zimmermann's injury on Monday, he and Justin Verlander are the only reliable starters the team has right now. Michael Fulmer was excellent in his last outing, but expectations have to be kept in check.

While the Tigers should be able to continue to man one spot from their young starters, only so much can be asked of young players making their early forays in major league level competition. Yet. any of a group consisting of Matt Boyd, Daniel Norris, Michael Fulmer or Shane Greene is likely to be an improvement over Pelfrey. Every one of them has better stuff to work with. Meanwhile, Anibal Sanchez still shows enough flashes of his past excellence to provide a glimmer of hope that he can stabilize his performance.

The original concept of acquiring Pelfrey had some merits. Putting a pitcher who gets a ton of ground balls in front of a better defensive infield than he's previous enjoyed made good sense. While the weakness of the Tigers' catching corps in terms of receiving pitches was a flaw in the design, the overall idea could have worked. Unfortunately, Pelfrey's sinker just isn't the same pitch he featured last season, and the margin for error was always extremely thin. The reality is a hole in the rotation that the Tigers can't be patient with much longer.

If not for the home runs ...

Mike Pelfrey is getting a lot of ground balls, as advertised, and his strikeout rate is about as good as it's going to get. You can look at less contact in the strike zone, and a higher swinging strike rate, and trick yourself into thinking things could improve. But his success last season depended on the lowest walk rates of his career and a low home run rate to boot. Both have spiked in the wrong direction this season, most particularly the painful amount of home runs he's given up.

Against a scuffling Phillies offense in Monday's game, Pelfrey still couldn't  produce a decent outing. Though he allowed no walks, he gave up a pair of home runs and 11 hits in just six innings of work. The Tigers' offense and bullpen bailed him out this time, but the team is getting nothing usable from Pelfrey right now. In nine outings on the year, he's yet to produce even one quality start.

As a sinkerballer, Pelfrey has to be able to live at the bottom of the strike zone. It's the only place in the zone he can throw pitches for strikes with any margin for error. And yet, he's getting hurt even in his sweet spot. He just doesn't have much he can throw in the zone without flinching right now. The result is almost entirely in the hitter's hands.

The reasons why his results are so much worse than in 2015 aren't all that clear. His sinker is down in velocity, from 93.3 mph last season to an average of 92.0 this year. For a pitcher already running with a slim margin of error, that modest decline may be having exaggerated results. Whatever the reason, hitters are having no trouble teeing off on him.

In addition, while the overall movement on his sinker is basically the same as last season, he's throwing it with a good deal more spin. For a sinker, more spin typically means the pitch doesn't sink. The decline in velocity may be masking the fact that he's not getting the late sink on the ball that he had last season.

Another factor is a tight strike zone. Whether due to Pelfrey's failing command, poor receiving from the Tigers' catchers, or a combination, he's not getting the benefit of calls at the bottom of the strike zone.

There's a lot of green in the bottom third of the zone, particularly in the corners. Maybe some of that is just bad luck and a small sample size of games, but he's not getting any help from the umpires. It's hard to know how much to pin on the catchers when Pelfrey is issuing this many walks. His command just isn't good, whether the catchers are contributing to the problem or not.

The scary part, is that there's really nothing left for Pelfrey to try either. He's increased the use of his split-fingered fastball already, but it continues to be hammered for home runs and extra-base hits, just like his fastball. Pelfrey throws his fastball over 65 percent of the time, so any decline in that pitch is going to be amplified. His batting average on balls in play is nearly identical to last year, so luck hasn't really factored into the equation either. The Tigers defense can't keep Pelfrey in the park.

The Tigers are going to have to come to a decision pretty soon. Certainly they're loathe to cut Pelfrey, and would likely try putting him into the bullpen before doing anything more drastic. At very least the Tigers need to hang onto him as insurance. Perhaps at least a temporary trip to the pen would allow Pelfrey to really air out his sinker and perhaps regain some modicum of effectiveness. The Tigers would have the option to try one of their young starters,  while having Pelfrey available in relief.

The Tigers already have Michael Fulmer in the rotation. They also have Shane Greene, Matt Boyd, who has been excellent thus far in Toledo, and Daniel Norris, all waiting in the wings. Any one of the four is potentially a better option than Pelfrey at this point. Young starters are unpredictable, but the potential to find a few quality outings seems a lot higher than it is with Pelfrey.

The question isn't whether the Tigers can win with two unproven starters in the rotation. The question is how much more proof the Tigers need to decide to take Pelfrey out. Between Pelfrey and Anibal Sanchez, the Tigers have two of the worst regular starters in the game thus far this season. Sanchez still has the stuff and the track record to be better than this. The Tigers aren't going to give up on him any time soon. The Mike Pelfrey experiment has to start showing results.