Say Goodbye to Sinkers and Cutters, Hello to Sliders and Whiffs

Yesterday, I took an early dive into leaguewide statistical trends on the hitting side. Obviously, it would be silly to evaluate hitters already, but not so for the league as a whole. Today, I switch over to the pitcher side. Since many of the metrics we would normally discuss are the same as for hitters that were discussed yesterday, let’s talk about pitch usage and plate discipline stats. Unlike yesterday when I was able to compare this season to just March/April of the previous four seasons, the Splits Leaderboard doesn’t give me the metrics I need. So rather than make more work for myself, all previous seasons are full season stats. Aside from velocities, it shouldn’t matter.

We’ll begin by checking on trends in pitch usage:

Remember when the cutter was the coolest pitch on the block? Going back to when Pitch Info data is available, cutter usage gradually rose from 2007, ultimately peaking at 7.6% in 2014. It’s been a steady downhill course from there and the early 2018 mark would easily be the lowest percentage during this period. Have teams determined that the pitch is too stressful on the arm? Aside from health concerns, I’m not sure why the downturn in usage.

Both splitters and sinkers are also down in usage, tumbling from their peaks notched a bunch of seasons ago. Again, these marks would represent lows since we have data going back to 2007. I guess moving away from the sinker matches with the data, as fly ball rate is increasing, and one explanation could certainly be a decline in sinker usage.

So with three pitches declining in usage, what the heck are pitchers throwing instead?! Sliders, basically, though this is just a continuation of a trend that began last season. Last year, slider usage spiked after first jumping above 14% in 2015. The upturn continued and it may have finally stabilized.

Now let’s check out velocity trends:

Obviously, it’s not totally fair to compare velocity in late March/early April to marks averaged from an entire season. We know that velocity rises throughout the season, but this table is still enlightening.

Notice that four-seam fastball velocity is actually right where it’s been for the full seasons of 2016 and 2017. If we expect it to increase from here, that means another record setting average fastball velocity.

Another interesting data point here is the rise in curve velocity. Oddly, a faster fastball hasn’t caused all tides to rise, as only the curve has increased in velocity of the secondary pitches. The changeup is nearly where it sat all of last year, so it’s very possible it ends up a five year high.

So batters are swinging at pitches outside the zone less often than ever, which is exactly what you want to see. Furthermore, they are swinging at pitches inside the zone more frequently, which, again, is generally a positive. Overall, though, the decline in O-Swing% more than offsets the increase in Z-Swing%, causing overall Swing% to drop to its lowest mark since 2010.

So batters have the right approach, but they can’t make contact! Their contact rates on pitches both in and out of the zone are at lows, with the in-zone contact rate tied with 2004 as the lowest mark since 2002, and the out-of-zone contact rate at its lowest since 2007. The inability to make contact pairs with another jump in SwStk%. Not surprisingly, it’s easily the highest mark since we have data going back to 2002.

Last, pitchers are throwing fewer pitches inside the strike zone and first pitch strikes. That supports yesterday’s increased walk rate.

There is probably less actionable data here than with the hitters. However, it does serve as a reminder that if you’re trotting out a bunch of 20% strikeout rate guys, you’re going to perform poorly in the category. That just doesn’t cut it like it used to.