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NRAA Glossary

Per reader request, a mini Net Runs Above Average Glossary.

Net Runs Above Average is calculated as follows:

[MLV(100/G) + (Rate2 - 100)] = NRAA/100 G

That number can then be divided by 100 to get the per game value of NRAA. That number can then be multiplied by however many games you wish to get rate n. I use per 100 games, per game, and per 162 in my spreadsheets, but any figure can be used.

MLV is Marginal Lineup Value. It is the cumulative version, rather than the rate stat MLVr.

Rate is the simpler version of the defensive metric; for the purposes of NRAA I use Rate2, which is adjusted for league difficulty.

There are other versions of NRAA though; eNRAA and pNRAA. eNRAA is Established Net Runs Above Average; this figures gives an established level of performance to better gauge future performances. Not as much of a projection as a guideline, with context taken into account. pNRAA is Positional Net Runs Above Average. This adjusts for position (really Marc? Does it now?). The formulas, for eNRAA and pNRAA respectively:


Firstly, find the EPL for MLVr:

MLVr EPL = (3 * PAx * MLVrx + 2 * PAy * MLVry + PAz * MLVrz) / (3 * PAx + 2 * PAy + PAz)

Where x = most recent year, y = second most recent year, and z = third most recent year

Then, find the EPL for Rate2:

Rate2 EPL = (3 * AdjGx * Rate2x + 2 * AdjGy * Rate2y + AdjGz * Rate2z) / (3 * AdjGx + 2 * AdjGy + AdjGz)

Where x = most recent year, y = second most recent year, and z = third most recent year

I use MLVr for eNRAA because I cannot get MLV from the PECOTA projection cards. I will need that information in order to work with the younger players who have not put in 3 years worth of time in order to weight their performance effectively.

After that, its time for a slightly different formula:

(EPL MLVr*100)+ (EPL Rate2 - 100) = NRAA/100 G

The same divide by 100, then by n rules apply to this formula.

Lastly, here is pNRAA:

[PMLV(100/G) + (Rate2 - 100)] = pNRAA/100 G

PMLV is Positional Marginal Lineup Value. This is the version adjusted for position, which basically gives centerfielders, middle infielders and catchers an extra boost, while taking away a little from corner guys. When comparing player X to player Y, as stated in comments, it has its uses. It also gives you an alternative to raw NRAA. This formula, just like the others, comes in the 100 and per game forms, as well as to n games.

I hope this will make it easier to follow the statistic, especially now since I believe it is done being tweaked. eNRAA on the other hand will most likely continue to be messed with until its time to project some performances. I should be uploading the spreadsheets once the website I would use starts working again, and then you can download them if you'd like. Or I can do this...

Net Runs Above Average 7-10-05 (Min. 150 PA)

Positional Net Runs Above Average 7-10-05 (Min. 150 PA)

If you would prefer to have the actual spreadsheet so you can sort stats, tell me.