Probably a question for PGStaff...
Why is there a consistent difference in velocity between stadium guns and TrackMan? I notice TrackMan (which I can read online) is usually 2-3 mph higher than a stadium gun.
I've seen this at multiple MLB, Spring Training and Triple-A ballparks.
Which is more accurate? My son tells me the clubs rely on TrackMan.
Replies sorted oldest to newest
Many of the stadium guns in both minor and major league stadiums are either slow or fast. TrackMan is almost always the same as a Stalker reading, both being extremely accurate. Though sometimes they all give a bad reading.
A pitch I was particularly interested in at a Spring Training game this past weekend registered at 90 on the TV feed, 92 in the stadium and 95 on TrackMan.
Wide range...interesting.
One year at our All American game the TV velocity was off by 6 MPH on the low side. The stadium radar was usually within 1 or 2 mph. TM and Stalker almost always within 1mph. TrackMan records velocity in hundredths, Stalker in tenths. So a Stalker reading of 1 mph difference from TM could actually be closer to two mph. TM reads 89.4, rounds off to 89, Stalker reading on same pitch is 90.5 and rounds off to 91.
At our complex in Georgia, TM readings are displayed on the scoreboard. This is very helpful to scouts and college recruiters. Knowing they are getting accurate velocity readings allows them to roam around rather than sit behind home plate. However, we use Stalkers there also and that is what we report. We only record peak velocity when a certain pitch is within one or two mph above other pitches. In other words if a pitcher ends up throwing 10 pitches at 89, 6 pitches at 90, 1 pitch at 91, and only one pitch higher and it was 95... We would record peak velocity at 91. Mainly because experience has shown us that no one really throws one pitch four or 5 mph better than all other pitches. Though it is possible in a very short outing, like facing one or two hitters. In that case we might record it.
While on this subject, we sometimes hear complaints from parents... Telling us that their son usually starts throwing much harder late in a game. There have been times that we have seen a pitcher maintain close to peak velocity for 7 innings, but after watching pitchers for so many years, thousands and thousands pitchers, we have never seen a pitcher that after three innings finally reached his peak velocity. The eyes might think they see it but the radar gun is more accurate.
Sorry for all of the above, just thought someone might be interested.
Yep on all of that. I know about the 1/10ths and I was just rounding off.
I went back and looked and I was slightly off. The specific pitch I referred to above was 93.6 (lowest of the day, first pitch of the day) on TrackMan for that pitcher. Stadium gun was 92 and TV was 90. So stadium gun coulda been 92.4 making it more in the 1 mph off range.
Peak velocity that day on TrackMan was 94.8 (twice). Every fastball was 93.6-94.8 on TrackMan. Highest stadium reading was 92.
I've seen this before. I'm in the stadium and see a pitcher at a certain velo. Different stadiums. When I look up TrackMan its almost always 2-3 mph higher, a few times even more difference. Just surprised, nothing more. I woulda thought stadium guns pump it up, not down.
I think there are stadium readings that are higher than actual Stalker gun or TM readings. However, I have no actual proof of that.
BTW, I'm guessing your interest involves Erik. Seems like he is throwing well in Spring Training. I wish him the very best and hope to see him back in the Big Leagues this year.
Yeah - Erik. Thanks. Obviously I pay more attention in that case and noticed this difference - and so the engineer in me was curious. Nothing more. Probably shoulda just put this in a PM.
TM is fascinating to me.
Fun to watch him pitch vs. Cubs last night. Sat 3 rows behind Tony LaRussa and just to my right and in front was Theo. Who knows who else? Fun time. 
