Seasons Are Arbitrary Endpoints

We often roll our eyes when announcers cite a player’s stats over the past 15 days. We’ll groan when they tout how many home runs he’s hit since the All-Star break. We’ll throw the remote when a pitcher’s last five starts are mentioned. And yet, when we attempt to analyze a player here, there’s nary a blink if ‘last season’ is mentioned.

Well, guess what. Seasons are also arbitrary endpoints. Yes, they are arbitrary endpoints that allow for easy analysis, and ones that we have all agreed to use. And, if we didn’t use them, statistical analysis would be rendered fantastically difficult. Our record books would look very strange. We’d have to phrase things very carefully.

But the fact remains, years can be as arbitrary as months and weeks. Consider this excellent comment by user James Lewis when confronted with the year-to-year power oscillation of Good Aubrey Huff and Bad Aubrey Huff:

Data start and end points.

If we instead turn Huff’s “seasons” into July ’04 -June ’05, July ’05 – June ’06, etc. we get a very different picture of the player:

Season 1: 0.176
Season 2: 0.186
Season 3: 0.186
Season 4: 0.203
Season 5: 0.222
Season 6: 0.157
Season 7: 0.173

Rather than bouncing up and down we see a steady development, followed by a down year, and a rebound in the final season. This is no less a description of Huff’s performance over time than any other delineation, and yet he doesn’t appear to be as “up-and-down” as we have come to expect. My guess is a lot of players show the same career path the Huff does, except they hide it better with the standard start and end points that we use – seasons.

Well that’s a very effective salvo for the commentariat and also one of the great benefits of having an open community of bright minds discussing baseball seriously. String together a couple bad half-seasons, in other words, and you’ll look worse than if you’d alternated those good and bad half-seasons. There is no Good Aubrey Huff, and there is no bad Aubrey Huff. There is only Aubrey Huff. Post-peak, perhaps, but still Aubrey Huff.

Naturally curiosity pushes us to find other Huff-like players. 32-year-old Vernon Wells has famously alternated good and bad years schizophrenically, as he has shown ISOs of .194, .239, .158, .197, .140, .242 and .169 since 2005. The yo-yo calms down dramatically if you switch to the July-June format as we did with Huff: .228, .171, .154, .176, .203, .179. The highs aren’t quite so high and the lows not quite so low. Now his current .169 ISO looks just about right for his recent history.

A similar story emerges for the Twins’ entry into the on-again-off-again derby, 32-year-strong Michael Cuddyer. Though his ISOs since 2004 (.177, .159, .221, .157, .120, .245, .146, .192) don’t perfectly fit the yeah-and-nope swings of a Wells or Huff, they do calm down some when you start a season in July and end it the next June (.152, .220, .190, .135, .219, .209, .153).

But there’s one player that fits this analysis to a “T.” There’s a certain portly 27-year-old slugger in Milwaukee that has shown more power in odd years than even, making some wonder if the team that signs him in free agency will have to endure a poor first year. Yes, it’s true that this former major leaguer’s son has ISO’ed the following, starting in 2006: .213, .330, .231, .303, .209, .264. And yet…

Prince Fielder’s ISOs from July to June:

“Season” ISO
06-07 0.265
07-08 0.266
08-09 0.274
09-10 0.264
10-11 0.246

Thanks to my many twitter friends for some of the names in this piece.

With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

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12 years ago

“Well, guess what. Seasons are also arbitrary endpoints.”

I’m not sure thats true. With the offseason, it could be argued that each season is a sample from a different distribution. Its much more likely that a player’s true talent level is constant over the course of a season than it is between seasons.

12 years ago
Reply to  RC

This is a great article. Very curious data presented. To address both the evidence here and the many factors that commenters are leaving: the title might more accurate as, “April-September Can Be as Arbitrary of a Sample as Random 30-game hitting streak.”

t ball
12 years ago
Reply to  RC

This is my thought, too. The fact that games are not played for 6 months, new players and coaches come and go through signings and trades, rookie promotions, etc. make the offseason a MUCH less “arbitrary” endpoint than any other sample, in my opinion.

The data presented above is interesting and we should always look beyond season-ending stats, but we already do that quite often. I have read numerous articles pointing out Batista’s late 2009-season power surge as a harbinger of his huge 2010, and we all know not to look at season stats for a guy like Dan Uggla and expect to get the whole story.

This seems like a solution looking for a problem, but the reminder to look beyond the obvious is always welcome.

12 years ago
Reply to  RC

You can argue anything, but if data says that some players don’t abide by your rule of separate distributions, what does that mean? What happens with the players whose true talent is constant between seasons then? What happens is exactly what Eno outlined here. Nobody says this works for every player, just some.

Arthur Xavier Corvelay
12 years ago
Reply to  RC

Speaking of arbitrary endpoints, that should be a colon in the middle. Subtle joke or just an ironic display of improper punctuation?

12 years ago

Wow I must confess you make some very trcenhant points.

12 years ago

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