Back to the shift: The Angels new infield

On Friday, the Los Angeles Angels signed Zack Cozart to a three-year deal, wrapping up a week-long whirlwind of activity. Adding Shohei Ohtani, Ian Kinsler, and Cozart to their roster certainly elevates them above most of the American League. Their roster isn’t perfect however. Even with the addition of Ohtani, their pitching staff resembles the Mariners pitching staff—they’re hoping for much better health and relying on a few too many bounce-back candidates. They’re likely the favorite to claim the second Wild Card spot at this point in the offseason but there’s not too much separating them from the Mariners or the Twins.

I want to take a moment to examine their new infield specifically. The Angels already employed the best defensive shortstop in the game in Andrelton Simmons. Adding Cozart to man third base and Kinsler to man second base will definitely be an upgrade over what they received defensively from those positions in 2017. As a group, the Angels third basemen cost the team -19 runs; their second basemen were much more acceptable at -1 DRS. Cozart is moving positions so we can’t guarantee a smooth transition but his defensive track record at short is very good. Kinsler’s defensive stats have been excellent throughout his career but he will turn 36 in 2018. They’ll probably play Albert Pujols at first base far too much with Ohtani taking some plate appearances away as the designated hitter.

Before I dig into the implications this new Angels infield has for the Mariners, I want to take a look at how the value of infield defense has changed recently. After Cozart signed on Friday, John Trupin asked me if I thought the infield shift was changing the way teams value infield defense. Obviously, a generational talent like Simmons will be valued highly no matter what. But if a team (say, the Mariners) can get by with a few average-ish defenders up the middle, shifting them around to mitigate their flaws, and get comparable defensive efficiency, why value individual defensive skill at all?

The best way I could think to visualize this was using a scatter plot. That way we could place teams into four different quadrants to easily compare them. On the horizontal axis is team defensive efficiency on all ground balls, the vertical axis is shift rate as a percentage of ground balls in play.

There’s a pretty minimal correlation between more shifts and higher defensive efficiency based on this dataset. On an overall league level, defensive efficiency is higher when employing a shift, but not all teams are created alike. Anyway, there are a few interesting things that immediately jump out at me when looking at this plot. Of the group of seven teams that shift far more often than any other team, the Mariners are the least efficient at turning ground balls into outs. Pwamp.

The most interesting point is probably the Cubs. Not only were they the most efficient at turning ground balls into outs but they also shifted the fewest times in 2017. The defensive combination of Addison Russell, Javy Baez, and Ben Zobrist allows them to position them normally and convert a huge amount of ground ball outs. I should point out that a team’s pitching staff plays an enormous role in the quality and amount of ground ball contact their infielders see. That aspect of the data isn’t reflected in the plot above but it’s an important point to remember.

Back to the Angels. In 2017, their defensive efficiency on ground balls almost exactly matched league average even though they shifted a little more than average. Their pitching staff skewed heavily towards fly ball contact so installing an elite defensive infield seems rather unusual. But I wonder if they’ve seen something in the data that will cause them to lower the number of shifts they employ in 2018. Russell Carlton posted an interesting article on Baseball Prospectus yesterday about ending defensive shifts. In that article he writes, “The shift appears to “work” because the hitters who get shifted against are (on average) lower-BABIP hitters.” He goes on to show how defensive shifting affects how pitchers pitch, leading to a tiny increase in balls per plate appearance, adding up to a significant amount during an entire season. Whether it’s from pitchers nibbling or feeling uncomfortable, or subconsciously changing their approach is unclear.

The data is too murky to definitively answer John’s original question. But I do think specific teams could reevaluate the way they use the shift based on their personnel. With three rangy defenders, some teams might be able to get away with more traditional alignments like the Cubs. The Angels have three excellent defenders installed in their infield now, we could see fewer shifts as a result and a similar or better number of ground balls converted into outs. If they continue to employ the shift as often as they did in 2017, are there diminishing returns on their ability to maximize their defensive alignment with three elite defenders? I don’t know and I wish I had the data to figure out a question like this.

So what does this all mean for the Mariners? Well for 19 games next year, it’ll probably be much harder to get a hit on a ground ball than it was in 2017. Below is a table listing each starter for the Mariners, their overall ground ball rate, and the rate those ground balls were hit in each direction.

The quartet of Jean Segura, Ryon Healy, Mitch Haniger, and Dee Gordon will probably lose a few hits when playing the Angels. These four put the ball on the ground often enough to probably feel the effects of facing a better defense. Gordon and Segura are probably fast enough to beat out some of these as infield hits but Healy and Haniger are the most likely to lose a hit or two. If the Angels end up shifting as much as this year, you could probably add Mike Zunino and Robinson Cano to that list of player who could feel the effects.