Major-league batters struck out in 21.7% of their plate appearances last season, an MLB record. That rate broke the previous record set in 2016 (21.1%), which broke the previous top rate of (20.4%) set in 2014 and matched in 2015. Major-league batters struck out last season at a rate five percentage points greater than in 2003. You’re probably well aware of this trend — a trend of more swing and miss, of fewer batted balls in play.

Reversing this trend seems difficult. It would require a change in incentives or, perhaps, the ball’s seam height. Batters would have to trade in power for more contact; pitchers would have to throw fewer breaking balls and with less velocity. The game keeps moving toward more power, more velo, more breaking stuff. It seems, at least to this author, that this strikeout level is pretty sticky and might continue increasing for the foreseeable future.

This phenomenon means a number of things. Most relevant to this post, it means that defenders have fewer opportunities, thousands fewer over the collective course of a season, which erodes the value of defense.

Some teams have been more aggressive with defensive placement, more willing to gamble to find a place for a bat, to trade defense for offense. The Indians stuck Jason Kipnis in center field late last summer, a position he had not played at all since the low levels of the minor leagues and not regularly since he attended Arizona State. (Kipnis posted a -3 DRS in 71 innings center). The Indians were also aggressive in slotting Lonnie Chisenhall in center earlier in the season despite his eight innings of previous experience there. Chisenhall, a college shortstop and professional third baseman turned outfielder, posted a 0 DRS in 164 innings in center, converting 34 of 36 Balls in Zone into outs.

Craig Edwards wrote about the curious case of Reds third baseman Nick Senzel trying out shortstop this spring. Craig wondered if we might see more players move up the spectrum, from third to short, in a similar way. After all, not only are fewer balls being put in play, but fewer balls are in play in the infield as ground-ball rate has declined in each of the last two seasons — and more and more batters are looking to launch.

While the makeup of a pitching staff and ballpark environment come into play when planning a defensive alignment, this decline of balls in play suggests teams could and should perhaps become more aggressive in finding ways to add more offense to their lineups. And maybe we’re already seeing that in this golden era of shortstops.

While players typically move down the defensive spectrum as they advance through professional baseball and age at the major-league level, perhaps batted-ball trends could cause more players to move up the defensive spectrum.

Overall, there were 60,249 “plays” by defenders in 2007, according to our data. Last season, there were just 49,809 — or roughly 10,000 fewer. A gradual year-to-year decline is evident over the last decade.

What I was really curious to learn is if certain positions were losing a greater share of opportunities or if the decline was spread relatively uniformly across the defensive spectrum. To simplify this study, there are issues to consider like defensive placement and alignment. I used the “plays” metric to capture opportunities handled by each position in the following chart over the last 11 seasons:

Where Have Defensive Opportunities Declined? Season RF Plays CF Plays LF Plays 3B Plays SS Plays 2B Plays 1B Plays 2007 8418 10886 8014 7221 10625 10120 4965 2008 7892 9684 7322 7403 10567 10525 4860 2009 7563 9609 7273 6943 10476 10149 4766 2010 7430 10086 6912 7220 10354 10380 4602 2011 6945 9116 6539 7366 10087 10395 5299 2012 6804 9129 6280 7238 9850 10181 5166 2013 6753 9210 6084 7197 9843 10049 5312 2014 6988 9466 6420 7138 9544 9699 5360 2015 6722 9053 5957 7037 9685 9504 5139 2016 6490 8555 5914 7161 8858 8615 4854 2017 6470 8552 6049 7008 8702 8140 4888 % Change -23.1 -27.2 -24.5 -2.9 -18.9 -19.6 -1.6

Not including catcher, five of the defensive positions that align themselves in fair territory have seen their play numbers drop by at least 19% compared to 2007 levels. Strikeouts have jumped by 25% over the last decade, and home runs are at record levels, too.

Interestingly, third base and first base have maintained relatively stable opportunity, whereas all three outfield positions — plus shortstop and second base — have had their opportunities drop significantly. Third basemen generally have been aided by defensive shifts, becoming responsible for covering a larger swath of territory.

If you prefer a visual presentation consider the following charts. One for most of the infielders…

And another chart of outfielder …

What does all this mean?

If a club has a ground-ball pitcher on the mound, perhaps it can be more aggressive in sneaking some additional offense into the outfield. If a team has an offensive-minded but large-framed shortstop, like a Corey Seager Carlos Correa, perhaps they could become less concerned with having to move him off the position. Instead of players generally always moving down the defensive spectrum, teams ought to consider candidates who can move up the spectrum — like Senzel — and more often trade offense for defense.

With teams more interested in roster flexibility than ever, versatile gloves that can hit become more valuable. Maybe we see more infield-outfield versatility among position players tied to their pitchers’ ground-ball rates. (While framing numbers have been erratic, catcher defense perhaps becomes even more important: its value is largely unaffected as it’s the lone defensive position in foul territory.)

Defense still matters a great deal. There’s always going to be a place and an interest in rostering elite gloves. There are still relative advantages, position to position, to be had defensively in this strikeout environment. Playing shortstop and center field still requires great athleticism.

Defenders just have fewer opportunities and those opportunities, to date, have not decreased uniformly.