## WPA vs. wRAA

I'm looking at the difference between WPA and wRAA as a tool for measuring leverage.

Background: I've got a coworker who has argued that Ichiro's hits come "when they don't matter."  I don't believe this is true and I'd like to test the hypothesis.  I think the best way to do this is WPA vs. wRAA.  My understanding is that wRAA is a straight linear-weights, context neutral stat that includes plate appearances, stolen bases, and caught stealing.  WPA only uses the same events, but is entirely context-dependent.  Taking the difference between the two should yield an answer on whether a player's contributions come in low-leverage moments.

I'm using Fangraphs as my data source, because they're awesome.

However, I have a couple of questions on the use of these stats to make sure that I'm doing this properly.

First: Do they, in fact, cover the same events?  (Or so close that I can get away with it.)

Second:  Which wRAA do I use?  There's the wRAA that's listed as such on Fangraphs, but then there's the batting component of WAR listed at the bottom of the page.  They're different, and it looks like the batting component of WAR is park-adjusted; should I use that?

Third: What's the conversion factor?  I know that +10 wRAA = 1 win.  And +0.50 WPA = 1 win.  So 10 wRAA = 0.50 WPA, and I can work the conversion from there, yes?  But then I start going around about the math and wonder if +10 wRAA gets you from 81-81 to 82-80, and is thus worth +1.00 WPA.  (And I'm aware that 10 runs = 1 win is a convenient abstraction, and the actual run value varies a bit from year-to-year.  And I'm wondering if that's significant enough that I need to account for it, or if I can use the standard 10 runs = 1 win.)

Or, am I attacking this problem from an entirely wrong angle, and there's a better way to do the analysis?  (Or even someone who's done the legwork for me, and I can point to the results?)

Thanks in advance for the help with the questions.

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