Comments on Basement Dwellers: Why do I keep using OPS?

The derivation and logic behind the 1.7 or 1.8*OBP...

2008-06-11T13:26:00.000-04:00

The derivation and logic behind the 1.7 or 1.8*OBP + SLG is detailed on my blog

As long as it's purely Q&D, then ok. Any ...

2008-06-10T10:32:00.000-04:00

As long as it's purely Q&D, then ok. Any other reason, then it's not ok.

Even here, you are testing at the team level, even though you have a large group of players that perform at outside the range of even the most extreme of teams. So, all you've really done here is test for players in the .320 to .360 OBP level (or whatever it is). But, the guys that interest us are outside this range.

And, there are teams that are outside this range. Create teams at the game level, by selecting those games where the OBP was at least .350 and SLG at least .450.

In fact, I already did all that in my Runs Created series, and those measures that aren't well constructed break down at those levels. And this includes Linear Weights and Runs Created.

@HFB:

Ok, I get these correlations:

2008-06-09T12:24:00.000-04:00
@HFB:

Ok, I get these correlations:

RPA (per AB): 0.9194
RPA into runs: 0.9198
RPA into runs (tango's conversion, which I think isn't quite right in this case): 0.9201

Better-tuned coefficients might work better, of course, as this was set only for 2007 AL (if I understand correctly).

@Tango,

Aside from my own personal OPS habit, a problem I run into is that a lot of the folks I target with my blog are only comfortable with OPS. If I start restricting myself to wOBA or R/G with everything I do, I'll have a harder time communicating with them.

Still, any time I do any kind of real analytical work, which isn't often these days, I do focus on R/G or wOBA... -j

"(27*(1+OBP))"

You want 27/(1-OBP)

S...

2008-06-09T09:34:00.000-04:00

"(27*(1+OBP))"

You want 27/(1-OBP)

So, if you have a .500 OBP, you need 27 outs and 27 times on base.

Greg Andrew is right that if all you want is Q&D, then OPS is fine. The problem is when people use it beyond the Q&D, and then we have to put up with crappy analysis as a result.

So, since people can't make the distinction, just take the weapon out of their hands and stop using OPS.

Justin,

I understand the differences in sam...

2008-06-09T07:19:00.000-04:00

Justin,

I understand the differences in samples. I will test it against other years, I just have to alter the coefficients a bit for the different run environments.

The equation you were using looks right, but in order to compare it against Runs per game, you have to multiply it by (27*(1+OBP)) to get runs per 27 outs and add 4.90.

Justin - Don't worry about using OPS. People have...

2008-06-09T00:32:00.000-04:00

Justin - Don't worry about using OPS. People have been questioning it since the beginning of time, and the answers to the questions remain the same. Yes, OPS is not properly weighted. Yes, it doesn't use any units. Neither of those things matter if you just use it as a quick 'n' dirty estimator. Obviously, no one should use OPS in a serious study. But there's no need to fix OPS when it's used as a rough estimate. And if something more exact or complicated than OPS is needed, you might as well use something a lot more exact and complicated.

Justin, I think I may have misled you with my "190...

2008-06-08T20:11:00.000-04:00

Justin, I think I may have misled you with my "1901 through 2007" comment. I'm actually not comparing stats across eras at all. (I know that I made another comment elsewhere about eventually wanting to be able to do this, but I'm not attempting it here.) I am only comparing stats within the same season and the same league. I think you'll like what I'm up to, actually. I guess we'll find out when I get it done. I'm up through about 1950 now.

Yes, I agree that absolute average approximates linear weight values in the way that I pointed out in my comment on the earlier thread: "Since OBP is undervalued in OPS, and walks are overvalued in OBP, it makes sense to correct the discrepancy by increasing the weight of the most valuable component of OBP, i.e. hits."

Hi there,

Hadn't seen that, but thanks for ...

2008-06-08T20:08:00.000-04:00

Hi there,

Hadn't seen that, but thanks for the heads up.

I will say that I don't think you can compare that correlation to those I reported here, as they're based on different samples and sample sizes. Correlations are notoriously "relativistic" stats, so you probably want to use 2005-2007 MLB team totals to get an apples to apples comparison.

I just tried to plug in your equation to my spreadsheet to get that correlation, but I keep getting a negative number, so I must be doing something wrong. Here's my equation:
=((-0.3149*(1-W4)) + (((((0.022*((X4/V4)^2)-(0.152*(X4/V4))+(0.607)))))*(X4))+(0.32*((W4-V4)/(1-V4))))

W = OBP, X = SLG, V = BA. I need to get going for a bit here, so I'll check this again later. But if you see my error, please let me know.

Thanks,
Justin

the (pseudo) linear weights formula i debeloped ba...

2008-06-08T19:51:00.000-04:00

the (pseudo) linear weights formula i debeloped based on BA/OBP/SLG had a R=.9329 for AL 2007.
http://hats-for-bats.blogspot.com/2008/06/rpa-numbers.html

i agree that linear weights is the way to go, especially when comparing across eras because just looking at the neutralized B-R stats doesn't take into account the more subtle differences in event values

That last bit sounds too harsh to me as I re-read ...

2008-06-08T17:54:00.000-04:00

That last bit sounds too harsh to me as I re-read it. I think my main point is just that if one is going to do a historical study comparing players across eras, one should really make at least some effort to adjust for the different environments across years, leagues, and teams. Simply comparing OPS or ABSO (or, for that matter, raw R/G or wOBA) won't let you do that. But you can use a combination of custom linear weights, park factors, and performance vs. baselines to do this.

So while you don't *have* to use linear weights by any means, there are a lot of advantages to doing so that extend beyond just the accuracy vs. runs scored argument (which is also a reason to use linear weights and not something else). So why not use them?
-j

@Dave, basically, if I'm going to use something ot...

2008-06-08T17:39:00.000-04:00

@Dave, basically, if I'm going to use something other than OPS, I might as well be using a linear-weights based statistic. :) I'm just so used to looking at OPS's scale that it's hard to use anything else that's not a dramatic improvement. Even linear weights aren't dramatic improvements... And besides, I'm so divorced from batting average at this point that I can't get used to evaluating players on that scale again!

@bluzer, the linear weights one uses should vary depending on the run environment. So yes, I'm sure that their accuracy would not be as good if used in a different era. But that's not an appropriate use of the statistics, so it's hardly a knock against them.

It's worth noting that OPS and your ABSO stat are also essentially a form of linear weights. You're combining values by summing them, not multiplying them in a way that allows for interactions (see Dan Fox's article). Therefore, one can't predict that OPS or ABSO will hold up any better than linear weights in different run environments. It's true that you can calculate ABSO or OPS (or lwts) for any player in history. And in general, the rankings within a year (and especially within a team) will be pretty good using OPS or ABSO or LWTS. But one shouldn't compare the raw values across eras, because the run environment is different in each era.

For example, Jimmy Wynn's 0.269/0.406/0.537 performance in 1969 looks impressive even today. But how much more awesome does it look when you realize that that a) he played in the astrodome, and b) NL hitters averaged 0.250/0.319/0.369 and scored 4.05 runs per game in 1969. Not 0.266/0.334/0.423 and scoring 4.71 r/g like they did in 2007. If you don't adjust for that difference, you miss out on a lot of his value. FWIW, B-Ref's "neutralize stats" button, set to 2007 NL in a neutral park, puts Wynn's 1969 performance at 0.309/0.485/0.582. ... which, if even close to being accurate, is pretty awesome, no?

I really think that it would be worthwhile for you to consider using linear weights to evaluate players. Honestly, I just don't see any reason not to do so. They are well-established in serious research circles, they're extremely accurate, and they're easy to use. And, with them, you can calculate custom linear weights for each runs environment (be it by league or by team, depending on your needs), adjust easily for park factors with decent accuracy (Patriot has published regressed park factors going back to ~1900 IIRC), and adjust to a relevant baseline for any given era (e.g. vs. average, or vs. replacement). There are established methods for doing all of these things (though the replacement level stuff is always contentious). And if you get really ambitious, you can try to adjust for quality of competition as well (which has increased quite a bit over time thanks to the huge influx of talent post-segregation and now with latino/asian players). So, again, I just can't see any reason not to use them...at least not if you're interested in assessing actual value, rather than finding some stats that better conforms to perceived value.
-Justin

Justin, thanks for doing this. It confirms my cla...

2008-06-08T13:08:00.000-04:00

Justin, thanks for doing this. It confirms my claim that absolute average is ABSOlutely better than OPS, although (in this sample, at least) not by as much as I would have expected. I took your advice and downloaded the Lahman database, and am currently working on my own historical study (1901 through 2007) to compare the two. I'll be looking at individual player stats rather than team stats, which may make a difference. I also think that the linear weights-based stats may have benefitted from the fact that the time period you used was roughly the same period over which the linear weights were derived.

And yet, no love for GPA? :)

2008-06-08T10:05:00.000-04:00

And yet, no love for GPA? :)

Comments on Basement Dwellers: Why do I keep using OPS?

The derivation and logic behind the 1.7 or 1.8*OBP...

As long as it's purely Q&D, then ok. Any ...

"(27*(1+OBP))"You want 27/(1-OBP)S...

Justin,I understand the differences in sam...

Justin - Don't worry about using OPS. People have...

Justin, I think I may have misled you with my "190...

Hi there,Hadn't seen that, but thanks for ...

the (pseudo) linear weights formula i debeloped ba...

That last bit sounds too harsh to me as I re-read ...

@Dave, basically, if I'm going to use something ot...

Justin, thanks for doing this. It confirms my cla...

And yet, no love for GPA? :)

"(27*(1+OBP))"

You want 27/(1-OBP)

S...

Justin,

I understand the differences in sam...

Hi there,

Hadn't seen that, but thanks for ...