Velocity Decline Trends for June, 2012-13

Well friends, we are now approaching that time of year where a significant drop in a pitcher’s velocity passes the 50% threshold in terms of signaling that they will finish the year down at least one full mph.

Month 1 mph Drop No 1 mph Drop Relative Risk
April 38% 9% 4.2
May 47% 6% 7.8
June 55% 5% 11.0
July 56% 4% 14.0
August 53% 6% 8.8

The table above breaks out the percent of pitchers who experience at least a 1 mph drop in their four-seam fastball velocity in a month relative to that same month a year ago and who also went on to finish the season down a full 1 mph. It also shows the relative risk — meaning, the increased likelihood that a pitcher will experience a true velocity loss at season’s end when compared to those pitchers that didn’t lose 1 mph in that month.

For example, pitchers that lost velocity in May finished the season down a full 1 mph 47% of the time, compared to just 6% that didn’t lose 1 mph in May — an increased likelihood of 7.8.

Here is your list of pitchers that lost at least 1 mph in June of 2013 compared to last June:

Now, remember, the relative risk outlined above and in previous studies only holds for pitchers that were in the same role (i.e. starters or relievers) in both 2012 and 2013. I’ve noted in the table which pitchers fit that criteria for 2013. The 2-Year Decline column notes if this pitcher suffered the same kind of decline the previous year (so, June 2012 compared to June 2011). I’ve also listed those pitchers where I had data on their velocity trends from May 2012 to May 2013, with negative values representing a velocity loss during last month.

Jason Marquis continues to pitch at a below-average level, posting a 107 ERA- and 163 FIP- so far in 2013. In June, Marquis saw his velocity decline for a second straight month relative to last year — 3.1 mph compared to last June after 1.4 compared to last May. Now, Marquis relies mostly on his sinker, but that pitch is also down relative to last year.

Matt Moore has had a bit of an up and down season, starting 2013 with 11 straight games where he gave up four or fewer runs. He then gave up six, nine, and five over his next three starts before his last three starts of three, one, and zero runs allowed. Moore’s biggest issue this season has been walks — after posting a 10.7% BB% last season he’s actually increased his walk rate in 2013 (12.6%). Lucky for Moore he’s decreased his HR/FB, so he hasn’t been hurt as much by the extra base runners he’s allowed. Still, I would keep my eye on Moore as his velocity declined 2.3 mph in May and 2.2 in June. It’s possible he’s trading velocity for attempts at better control, but he has pretty much been down the entire season and his walk rate has not improved significantly over time.

The other interesting name for me on this list is Zack Greinke. It’s true that Greinke’s velocity could be off a bit given that he missed time with a broken collarbone, and that was after some elbow drama during spring training. However, he came back from the disabled list in mid-May and he’s suffered velocity loss in both May and June. Greinke has been slightly below average in terms of ERA and FIP and is now sitting around 90-91 mph on average with his fastball. He is in his age-29 season, so it wouldn’t be all that odd to see him starting to lose more significant velocity. On average, starters lose about .5 mph between ages 28 and 29 and that begins the steeper decline portion of their aging curve. Strikeout rate, which is also down about 6% this year for Greinke, also begins a steeper decline around 29-30 years of age as well.

Oh, and one of the happiest teams with this list? Probably the Yankees, since CC Sabathia isn’t on it. Yes, he still posted a lower June velocity than last year (-.7 mph), but he’s below the 1 mph threshold and that’s an improvement based on his April and May (down -1.9 mph in both).



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Bill leads Predictive Modeling and Data Science consulting at Gallup. In his free time, he writes for The Hardball Times, speaks about baseball research and analytics, has consulted for a Major League Baseball team, and has appeared on MLB Network's Clubhouse Confidential as well as several MLB-produced documentaries. He is also the creator of the baseballr package for the R programming language. Along with Jeff Zimmerman, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Twitter @BillPetti.


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