A little past the halfway mark of the season, the Cubs have very few areas of real concern. The offense is one of the very best in baseball. The starting pitching has been healthy and extraordinary (with a few bumps in the road lately). The biggest concern throughout the first half has been with the bullpen. Rondon and Strop have both been very good, but getting the ball to them has been a big challenge.
In 2015, there was a third reliever in the pen that posted fantastic results - Justin Grimm. But 2016 has been something of a nightmare for Grimm (or for the fans when he pitches). While he has been better than his 5.79 ERA would suggest, he has still been pretty bad. The 4.42 FIP and 4.12 xFIP both point to a reliever that cannot be relied upon in close games.
So is there any hope that Grimm returns to his 2015 level of performance? Let's take a look at some charts!
First off, it is always good to look at how things are trending - are they getting better or worse? In this case, it doesn't take a statstician to spot the trend here. Grimm's season started out pretty good in April and has been on the fast track to disaster ever since. We did see that his FIP (fielding independent pitching) and xFIP (expected FIP, which normalizes home runs per fly ball) are better than his ERA. Let's add those to the chart and see those trends.
Honestly, that's not much better. At this point, I wanted a little more context and so I added in 2015 to the chart and was pretty depressed at the results.
Grimm was fabulous last year...until around August. His rapid descent into the independent leagues actually started last year. So what the heck happened?
So, to sum up that chart: each year has seen steep declines in strikeout rates and sharp increases in walk rates during the times he's struggled. To show why that's the case, particularly in 2016, I now present the rolling average of his swinging strike percentage, or how often he can get hitters to swing and miss:images/articles/2016-07-06/swinging_strike.png
That doesn't explain a lot in 2015, but this year Grimm has generated less breeze from whiffs than a broken fan. So, let's dig deeper. Has he lost velocity?
The trend this year isn't great, but he started out higher than he ever had been. He's still around the same speed as when he was really good to start last year. Has he lost movement on his pitches?
Nope. Both of those trend lines are awfully stable. Well, maybe the "both" part of that is significant. This year, Grimm has really focused on his four seam fastball and his curve. That was also the case last September and October when his results collapsed.Let's take a look at some stats on those. First, let's look at usage rates for the pitches.images/articles/2016-07-06/pitch_selection.png
He has pretty much totally ditched the slider in favor of the curve. How effective are the pitches?
This chart shows the value of the pitches per 100 thrown. When he was using the slider last year, it was significantly less valuable than the curve. But this year, the slider has worked really well for him the few times that he's used it. The value of his fastball has pretty well collapsed this year, too.What I suspect is going on here is that hitters are able to pick up on the difference between his fastball and his curve. When he was throwing the slider, it made his fastball more valuable because hitters had something else to think about after they ruled out curve ball. Now they seem to be able to sit on the fastball and do a lot more damage to it than in the past.
So, maybe there is hope for Grimm. Let's hope he brings back the slider.