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There has been something weird going on in baseball over the past few seasons. To wit:

Year 1B_RT 2B_RT 3B_RT SS_RT LF_RT CF_RT RF_RT
2003 0.1713 0.2919 0.2351 0.3017 0.3193 0.3712 0.3095
2004 0.1695 0.2879 0.2368 0.3058 0.311 0.3706 0.3184
2005 0.1711 0.2877 0.2369 0.3043 0.3172 0.3687 0.3141
2006 0.1666 0.2873 0.2402 0.306 0.3186 0.3702 0.3112
2007 0.1686 0.287 0.235 0.3095 0.3232 0.3699 0.3068
2008 0.1706 0.2874 0.2382 0.3037 0.3171 0.3706 0.3123
2009 0.1735 0.2829 0.2374 0.3062 0.3163 0.3735 0.3102
2010 0.1694 0.2855 0.2373 0.3078 0.314 0.3738 0.3122
2011 0.168 0.2903 0.2324 0.3093 0.3162 0.369 0.3148
2012 0.168 0.2935 0.2288 0.3097 0.324 0.3713 0.3047

That's the rate of all BIP fielded by each position, compared to its group (so infielders and outfielders each sum to 1 as a group).

What we see over time is an increase in balls fielded by the shortstop and second basemen, among other things. (This holds true if you ignore this season, which is barely under way.) Third base and first base see corresponding drops. In the outfield, we see left fielders picking up more plays relative to right fielders.

To see what's going on, let's split it out by batter handedness. First, right handers:

YEAR 1B_RT 2B_RT 3B_RT SS_RT LF_RT CF_RT RF_RT
2003 0.1134 0.2275 0.307 0.3521 0.318 0.3717 0.3103
2004 0.1098 0.2258 0.3072 0.3572 0.3166 0.3686 0.3148
2005 0.1116 0.2218 0.309 0.3576 0.3206 0.3693 0.3101
2006 0.1128 0.224 0.307 0.3562 0.3179 0.3712 0.3109
2007 0.112 0.223 0.3022 0.3627 0.3206 0.3722 0.3072
2008 0.1109 0.2212 0.3116 0.3563 0.3131 0.3709 0.316
2009 0.1111 0.2156 0.3102 0.3631 0.3099 0.3773 0.3128
2010 0.111 0.2186 0.3083 0.3621 0.3056 0.3778 0.3166
2011 0.1074 0.2188 0.3045 0.3693 0.3104 0.3752 0.3143
2012 0.1051 0.2172 0.3001 0.3776 0.3149 0.3824 0.3027

Balls hit to the shortstop is on the uptick, with a corresponding decline in the number of balls hit to the second baseman. In the outfield, things get really weird, with the ball seeming to shift more to left and center, and right field declining.

On to left-handers:

YEAR 1B_RT 2B_RT 3B_RT SS_RT LF_RT CF_RT RF_RT
2003 0.2521 0.3818 0.1348 0.2313 0.321 0.3705 0.3085
2004 0.2522 0.3739 0.1393 0.2345 0.3035 0.3732 0.3233
2005 0.253 0.3785 0.1376 0.2308 0.3126 0.368 0.3195
2006 0.249 0.3842 0.1377 0.2291 0.3197 0.3686 0.3117
2007 0.252 0.3814 0.1357 0.2308 0.327 0.3667 0.3063
2008 0.2544 0.3804 0.1353 0.2299 0.3226 0.3702 0.3072
2009 0.2563 0.3721 0.1407 0.2309 0.3246 0.3687 0.3068
2010 0.2548 0.3835 0.1334 0.2283 0.326 0.3681 0.3059
2011 0.2511 0.3882 0.1336 0.2271 0.3237 0.3609 0.3154
2012 0.2492 0.3919 0.1368 0.2222 0.3353 0.3576

0.3072

This time we see more balls to second and fewer balls to short, the opposite of what we saw above. The outfield looks similar, albeit more pronounced—more balls to left, fewer balls to right (but with a decrease in balls to center, unlike the right-handed hitters).

What to make of it? Maybe it's nothing, but it feels like something is going on. It could have to do with how hitters are pulling the ball, or how teams are positioning or assigning fielders. (In the outfield I feel like there's some of each going on, actually.) I don't know what it all means, exactly, but I think it's worth investigating in more detail.