Jason
@jasoner.net
Cubs fan. Trying to make a sabermetrics blog, blog.jasoner.net
@pobguy.bsky.social When using your baseball equations of motion, to account for wind, can I simply substitute (v - v_wind) for v, v_z - v_(wind in z direction) for v_z, and so on?
September 14, 2025 at 2:40 AM
@pobguy.bsky.social When using your baseball equations of motion, to account for wind, can I simply substitute (v - v_wind) for v, v_z - v_(wind in z direction) for v_z, and so on?
That term doesn't necessarily have to be constant though. I don't see why the PA term has to be the league average PA/IP instead of the pitcher's individual PA/IP. Wouldn't that fix the bias from better pitchers having fewer PAs?
June 26, 2025 at 1:08 AM
That term doesn't necessarily have to be constant though. I don't see why the PA term has to be the league average PA/IP instead of the pitcher's individual PA/IP. Wouldn't that fix the bias from better pitchers having fewer PAs?
So if this observation is correct (and I have no clue why it would—it seems VERY wrong) it would appear that the correct formula for wRC would be something like wRAA + lgR/G * TG. Trying this out, we can see the relationship is significantly closer to expected (maybe it should be lgR/out * outs?)
May 31, 2025 at 6:00 AM
So if this observation is correct (and I have no clue why it would—it seems VERY wrong) it would appear that the correct formula for wRC would be something like wRAA + lgR/G * TG. Trying this out, we can see the relationship is significantly closer to expected (maybe it should be lgR/out * outs?)
...it appears that they are expected to score the same number of runs assuming they've both played a whole season, because there is no relationship between the number of runs that is average (R - wRAA) and PA (excluding the 2020 season).
May 31, 2025 at 6:00 AM
...it appears that they are expected to score the same number of runs assuming they've both played a whole season, because there is no relationship between the number of runs that is average (R - wRAA) and PA (excluding the 2020 season).
Ok I think I figured out the issue with wRAA vs RAA. The issue is that teams who score more runs have a higher "average" by my formula due to having more PAs, which suppresses their RAA slightly. I'm not quite sure why the same thing doesn't happen to wRAA (surely the average number...
May 31, 2025 at 6:00 AM
Ok I think I figured out the issue with wRAA vs RAA. The issue is that teams who score more runs have a higher "average" by my formula due to having more PAs, which suppresses their RAA slightly. I'm not quite sure why the same thing doesn't happen to wRAA (surely the average number...
Obviously an approximation but 27 outs per game should be close enough, still getting the same result. Outs/G is slightly lower than 27, but not by a ton.
Also: wRAA and RAA aren't per PA, so if the issue was using the wrong denominator, the wRAA vs RAA regression wouldn't have the same issue
Also: wRAA and RAA aren't per PA, so if the issue was using the wrong denominator, the wRAA vs RAA regression wouldn't have the same issue
May 30, 2025 at 4:38 PM
Obviously an approximation but 27 outs per game should be close enough, still getting the same result. Outs/G is slightly lower than 27, but not by a ton.
Also: wRAA and RAA aren't per PA, so if the issue was using the wrong denominator, the wRAA vs RAA regression wouldn't have the same issue
Also: wRAA and RAA aren't per PA, so if the issue was using the wrong denominator, the wRAA vs RAA regression wouldn't have the same issue
I also see a very similar result when comparing wRAA and RAA (runs above average, comparing the number of runs a team scored to lgR/PA * the team's number of PAs) where wRAA assumes the team will have a higher magnitude of RAA than they actually do (farther from the mean of 0)
May 30, 2025 at 3:19 PM
I also see a very similar result when comparing wRAA and RAA (runs above average, comparing the number of runs a team scored to lgR/PA * the team's number of PAs) where wRAA assumes the team will have a higher magnitude of RAA than they actually do (farther from the mean of 0)
Doesn't seem like a change in bat speed in the first month vs last season correlates with a change in xwOBA for the rest of the season. This somewhat makes sense to me, because a bat speed reduction is likely intentional, as indicated by these changes in bat speed generally sticking around
May 4, 2025 at 2:04 AM
Doesn't seem like a change in bat speed in the first month vs last season correlates with a change in xwOBA for the rest of the season. This somewhat makes sense to me, because a bat speed reduction is likely intentional, as indicated by these changes in bat speed generally sticking around