Position by position, offense is trending together

Offense is down slightly across baseball, a possible or probable consequence of an increased emphasis on defense. This makes intuitive sense -- a team that cares not at all about defense would prefer the tiniest of offensive advantages over the largest of defensive disadvantages. But not all teams are the Phillies, and the other 29 seem to be moving in the other direction toward valuing defense, or run prevention more generally. I'm not sure whether we're all the way to equilibrium yet; at equilibrium, a run saved by fielding should be viewed equally to a run earned at the plate. As partial win values on offense get cashed in for larger win values on defense, though, overall offense should trend downward.

But that doesn't mean offense will trend downward equally, across all positions. Will defense be prized all across the diamond, or evenly? A quick look at wRC+ should shed some light on whether that's already been happening. If offense is down overall, that wouldn't be reflected in wRC+. The statistic is perfect, however, for showing whether offense has been evened out across positions or if the chasm has sharpened.

The stats more or less speak for themselves, and so here's wRC+ by position for the last twenty seasons (remember, 100 is average for non-pitchers):

Although there's nothing drastic in the statistics in this table, there are a few things that jump out for me, anyway. Remember, even though there's a lot of year to year noise here, we're talking about enormous samples, with each cell in the above (except for DH) a combination of about 35 seasons' worth of at bats.

Flattening out across the diamond

On a position level, catcher is pretty interesting. Hitting from the catcher position is definitely on the rise, as Beyond the Box Score's Jeff Wiser recently wrote about the NL. In the last twenty seasons, only catcher has ever dipped below the wRC+ for shortstops, and yet in the last few seasons, wRC+ for the catcher position has been competitive with third basemen and better than second basemen. From 1994 to 2003, the average wRC+ for the catcher position (by year) was just under 87; in the more recent ten years, it was just under 89. That's not nothing, although your guess on why is as good as mine.

It could be that offense is flattening out across the diamond. Note that in the last several years, the wRC+ from first base has decreased slightly (average of just under 114 in 1994-2003, average of 111 in 2004-2013). Center field tended to be a slight liability in the first half of the period, but remarkably average in the last several years. Left field moved similarly, but in the opposite direction. And the standard deviation among positions year to year has decreased:

That seems to be a pretty clear trend to the middle over the last twenty years. There's just less variability from position to position now than there once was.

Again, your guess is as good as mine. Something is going on here. Is it that teams have worked harder to keep premium hitters at premium positions? If players like Xander Bogaerts were once relegated to third, etc., and are now more frequently kept at premium positions if possible, that could be a partial explanation.

Another potential partial explanation: teams have learned that impact defense need not come up the middle. Manny Machado may stay at third if he's an outstanding defender there and not quite as stellar at short -- your premium defense need not come from premium defensive positions. If so, that seems not to have affected right field.

Right field: remarkably consistent

In the last twenty years, the wRC+ for right fielders has been eerily consistent. Managing a peak of 109, the lowest wRC+ for RF in the last twenty years is 104, a mark which was set four times. Right fielders had a wRC+ of 108 a ridiculous seven times in the last twenty seasons, including five seasons in a row. What gives? The standard deviation of wRC+ points for RF is 1.7, a healthy step below the standard deviation for center field (2.1), first base (2.2), and shortstop (2.6). Second base and third base are next (3.1), followed by left field and catcher (3.3), and well behind DH (4.0).

I'll hazard a guess as to why. At center field, right field, first base and shortstop, teams know exactly what they want. It would be unusual for the industry to suddenly tolerate hitting from first basemen that was worse than above average; unusual for an entire generation of better-hitting shortstops to emerge, etc. In contrast, left field is often the last position on the diamond filled by front offices, which might lend to more variability. The same goes for the DH, although the smaller sample size for each year would also explain the high standard deviation for DH.

I'm not sure if that's the right theory, and maybe someone will tell me that these differences in standard deviations is not significant. But because they seem predictable (with the most specialized positions, like SS and 1B, being the most stable), I tend to think there's something here.

If so, what does that say about right field, the most stable of positions from a wRC+ standpoint? It did not occur to me that front offices might view right field so rigidly. And considering that right field tends to "require" a physical tool (throwing arm) that matters much less in left field, I think it's surprising that RF has consistently out-hit LF by about 3 wRC+ points every season.

I think the stability of the right field wRC+ marks reveals that front offices have indeed viewed right field more rigidly. Second base and third base may be more variable because different types of skill sets are tolerated there (although that's a conclusion that would be better made in team-to-team statistics for a given season). Gerardo Parra has been a tough nut to crack because of his standout defensive performance there (in 2013, he tied Andrelton Simmons in setting the season record for Defensive Runs Saved in a season). It was really difficult to come up with arbitration comparables for him. And Parra's case may support this premise -- even in left field, different skill sets are tolerated, but in right field, not so much. It may be that the main variable for right fielders is defensive ability (mostly range?), not offensive ability.

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All statistics courtesy of FanGraphs.

Ryan P. Morrison is a featured writer at Beyond the Box Score, and co-author of Inside the 'Zona, a site on the Arizona Diamondbacks with a sabermetrics slant. You can follow him on Twitter: @InsidetheZona.