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:

ISOs:
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:

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