So far this season, the GPS location reports have been a bit of a mixed bag. Before the season began I talked about Zach Plesac who has struggled mightily against teams not named the Tigers. Then, we discussed Brady Singer’s ability to generate called strikes, and last week I wrote up Pirates’ pitcher JT Brubaker, who went out a threw a gem last Friday. Today I am going to discuss a pitcher who was a waiver wire target of many this past week, Alex Cobb.
Cobb once posted back-to-back sub-3 ERA seasons in 2013 and 2014 for Tampa Bay but after that injuries and poor performance have really hampered what appeared to be a once-promising career. Never a strikeout artist, Cobb’s best pitch has always been his splitter. However, on the back of a pitch mix change, Cobb’s strikeout numbers have shot up as he’s posted a K% over 30% thus far in the short sample well above his previous career-high of 23%. So the question that many have is, how is he doing it, and is it sustainable?
When discussing Alex Cobb or anyone this early in a season it is important to note that it is still early and Cobb has only thrown 11 innings. However, when you go to Cobb’s Savant page one thing stands out.
His splitter usage has been rising steadily over the last few seasons, but in 2021 he has taken this to new heights. He now throws his splitter almost half of the time. However, a more underrated change has also been an increase in his curveball usage. So now, he is throwing non-fastballs on almost a third of his pitches. This a huge upgrade for Cobb as both of those pitches have historically posted whiff rates in the 20-30% range. This is a small sample but I am willing to believe the mix change is real especially after we saw similar changes for Dylan Bundy within the same organization. One thing that we tend to overlook with a pitch mix change though, is the impact that it can have on a pitcher’s command.
Based on the way that I grade command, rfCommand, which can be found on the RotoFanatic Data Monster, we are easily able to see the impact a pitch mix change can have. “Command” is a loaded term and each person you talk to will define it differently. However, rfCommand is based on expected results (whiff, swing,wOBA) due to a given pitch’s location. Everything we know about non-fastballs tells us that throwing them instead of a four-seam or sinker typically leads to more whiffs, poorer contact, and better swing results for pitchers. So by extension, optimizing a pitch mix typically leads to improvement in rfCommand. Cobb is certainly no different in that sense. Below are his rfCommand grades dating back to 2015 as well as his StuffERA figures.
As you can see for much of his career, Cobb has had well above average rfCommand (0 is average) but 2021 has been a completely different level. He has made improvements across the board with all of the components of rfCommand, but the most significant jump has been his xWhiff rates. His previous career-high was 0.123 (12.3%) but so far in 2021, he has been at 0.138 (13.8%) a 1.5% point increase. As discussed before, the splitter has been the biggest driver of this change.
As you can see thus far, Cobb has been excellent when it comes to keeping the splitter down in the zone and at attacking the locations with high expected whiff rates. While the added whiffs are massive for Cobb, the chart below highlights the importance of the location even more.
Looking back at the earlier career numbers for Cobb, the splitter while generating a ton of whiffs also got hit pretty hard. This is something I have noticed with a number of other prominent splitter-heavy guys like Masahiro Tanaka and Frankie Montas. The pitch, while great, can also tend to be left over the plate too often and when it does it flattens out and becomes extremely hittable. I have not done the pure research on this but from my anecdotal experience, pitchers who rely on splitters for an outpitch tend to be a bit more homer prone. But what you are seeing above, is that Cobb has been absolutely exceptional with the splitter to this point. He is keeping it down in the zone and when he does miss up its tends to be off the plate as well. He has done a masterful job of avoiding the red spots within the zone with the pitch.
Moreso than the added whiffs, this will be the key to Cobb’s improvement this season. For fantasy managers, we want to see the insane K-jump continue for in order for Cobb to keep that ERA low the more important factor will be keeping the splitter down in the zone. If he can do that, he can avoid the long ball and the Ks will keep racking up. I am in on this mini-breakout and will be watching his next few starts closely to see if this incredible command can continue.