Defense Metrics
There are two big caveats using these defense metrics in college:
It's all trained on MLB data, not college data.
Trackman's calibration is not great in many parks. If we get a location 6 inches off the real location of the ball as it crosses the plate, these models are going to output bad data in those cases.
Catching
[SL+] = Strikes Looking Rate vs Average
SL+ is a rate stat that expresses actual called strikes over expected called strikes. Scores above 100% mean more strikes are called than were expected.
[SLAA] = Strikes Looking Above Average
SLAA is actual called strikes minus expected called strikes. So SLAA above zero means more strikes were called than expected. SLAA is measured in called strikes.
[FrmRAA] = Framing Runs Above Average
FrmRAA puts those called strikes on a linear weight runs scale.
The run value is based on MLB data and takes handedness of the batter and pitcher into account. Roughly adding an extra strike is worth about 0.06 runs and adding an extra ball is worth about the same, so the net impact is about 0.12 runs, but it's weighted by the probability of a called strike.
So if a pitch with a p(called strike)=0.3 gets framed well and called a strike, the catcher added about 70% of a strike and added about 0.7 * 0.06 = 0.042 runs. That 0.042 runs is the FrmRAA value.
[FrmCntRAA] = Framing Runs Above Average - Count Sensitivee
FrmCntRAA is the same thing but it factors in the run value differences between counts. Getting a framed strike on a 3-2 pitch is way more valuable than getting it on a 2-0 pitch.
Infield Defense
[IFChances] = Infield Chances (Fielding)
Balls hit to the area of the field where the player is playing (independent of exact positioning).
[IFGBOutPM] = Infield Outs Plus/Minus (Fielding)
Standard plus/minus stat, with the player getting +0.7 outs for a ball that is caught 30% of the time, etc. (Again, ignoring positioning)
[IFGBWOuts%] = Weighted Infield Out Rate (Fielding)
Puts the plus/minus counting stat on a scale with 100% being average.
[IFGBRunsPM] = Infield Runs +/- (Fielding)
Converts the plus/minus into runs. Saving a double is more valuable than saving a single, etc.
Outfield Defense
[OFAirBall] = Outfield Chances (Fielding)
Balls hit to the area of the field where the player is playing (independent of exact positioning)
[OFOutsPM] = Outfield Outs Plus/Minus (Fielding)
Standard plus/minus stat, with the player getting +0.7 outs for a ball that is caught 30% of the time, etc. (Again, ignoring positioning)
[OFWAirOuts%] = Weighted Outfield Out Rate (Fielding)
Puts the plus/minus counting stat on a scale with 100% being average.
[OFRunsPM] = Outfield Runs +/- (Fielding)
Converts the plus/minus into runs. Saving a double is more valuable than saving a single, etc.