In 2016, baseball set a new record low for intentional walks per game. That broke the previous record, set in 2015, which had broken the previous record, set in 2014, which had…you get the idea. Between 2006 and 2016, the total number of intentional walks fell by almost 500, from 1410 down to 931.

It has been over a decade since The Book made it explicitly clear that intentionally walking hitters was a significantly overused strategy because it actually made the run expectancy go up in the majority of situations. The value of getting to a weaker hitter or creating a double play opportunity is often outweighed by the penalty of putting another runner on base, unless there is a massive gulf between the quality of the hitter on deck and the hitter at the plate and a specific base/out state is occuring, particularly men on second and third with two outs. Teams have been responding to this fact ever since, as the numbers show.

Something changed at the start of 2017, though: pitchers no longer had to throw four intentional balls to issue the walk. Now they could bypass the process altogether and simply let the batter wander down to first base. One might think that reducing the chance of an intentional ball going wrong from miniscule to zero wouldn’t have an effect on intentional walk rates. After all, none of the other factors have changed, and wild intentional balls are pretty rare. And yet:

Yes, it’s just a small difference, but 2017 marked the first time intentional walk rates went up in six years. In total there were 38 more issued than 2016. Maybe this was just a blip. After all, it’s still the third-lowest rate of all time. It’s not as though managers suddenly exclaimed “Finally! Now I can put a guy on first without my pitchers throwing wild intentional balls!” and enthusiastically went back to walking hitters at late-’60s levels.

Nonetheless, there must have been some managers out there who were slightly more willing to point, or wave, or tip their cap, or perform some kind of interpretive dance, in order to send hitters automatically to first. Here are every team’s intentional walk totals for the past two years, sorted by the change:
 

Intentional Walks by Team, 2016-17

There’s a lot of noise here, of course. Some teams will get into more extra-inning games and late inning tie situations where the intentional walk makes more sense. Some teams will naturally face more situations where there is a huge gulf in quality between consecutive batters. Some managerial changes and tendencies can be seen here too: Walt Weiss donated free passes far less often than Bud Black; the same could be said for Torey Lovullo relative to Chip Hale. Don Mattingly loves the intentional walk; he has issued 121 in just two years since taking over as Marlins manager.

There are some big jumps from returning managers there too, although the leader isn’t going to have a major league job next season. Brad Ausmus called for the most walks of his four-year tenure with the Tigers for the biggest gain and is all but certain to be issuing zero in 2018. Another manager whom most fans wish would get fired surged to the league’s third-highest total in St. Louis, but Mike Matheny kept his job anyway. Perhaps most intruiging is the league’s two most IBB-averse managers in 2016 more than doubling their totals in 2017, although it could just be simple regression to the mean.

Nonetheless, Ned Yost is an example worth talking about. 2017 was the first time since 2013 that he did not issue the fewest intentional walks in the league. Yost has never called for more than 44 free passes since taking over as Royals manager and has routinely been one of the most unlikely managers to hand them out since he did that in 2012. This might be at odds with the old-school reputation that Yost has, so rest assured that he still manages to use them in some of the most infuriating, illogical situations possible.

Were there any pitchers that were suddenly issuing intentional walks now that they didn’t have to gently lob four balls somewhere in the vicinity of home plate? The next table is every pitcher who had an increase of at least four intentional walks from 2016 to 2017.
 

Largest Increases in Intentional Walks, 2016-17 (min 50 IP per season)

It’s not hard to see where Matheny handed out a lot of those extra walks. Seung Hwan Oh led the league in intentional walks. It was the first time since 2013 that a single player had intentionally walked as many as nine in a single season.

It wasn’t as though Oh was incapable of intentionally walking hitters, or lacked control. He had 13 before he arrived in the U.S. and three more in his debut season. This seems likely to be more related to circumstance, a decline in Oh’s performance from his stellar debut, and an associated lack of trust from Matheny. There was one period in May where Matheny called for five of those walks in just eight appearances, spread over three weeks.

Sam Dyson‘s surge is most likely to be related to Jeff Banister than his own personal skillset: Banister has issued the seventh-fewest intentional walks in the three years since he took over as Rangers manager, and has cut down even more in the past two seasons. Dyson did not have a single IBB with Texas and only picked up his seven after arriving in San Francisco, where Bruce Bochy has fewer qualms about the maneuver. Dan Jennings looks like random fluctuation altogether. His 2015 total was six walks, with the same manager as 2016 (Robin Ventura). It’s possible that this is the trust issue appearing in reverse, as Jennings had a 2.08 ERA in 2016, almost halving his 3.99 from 2015 despite almost identical peripherals.

Chad Kuhl is the case that looks like it might be most related to the issue of not actually wanting him to throw the intentional balls. Kuhl had never issued an intentional walk as a pro, going over 400 minor league innings and then another 70 major league innings in 2016 without one. There were flashes of wildness – 20 hit batsmen across his first 41 minor league starts – but overall the control was good up until 2017, when his walk rate jumped to 10.6 percent and he uncorked 8 wild pitches with 6 more hit batsmen. That might have made Clint Hurdle happier to call for the free pass in 2017, yet it doesn’t explain why Kuhl had never been asked to do it prior to 2017.

There were four players on the mound for three IBBs in 2017 who had never previously issued one in the majors: Matt Boyd, Zach Davies, Chris Devenski, and Daniel Norris. However, most notable is a fifth player with three, who had simply not thrown one for a very long time: Jon Lester. The 34-year-old has infamous issues with throwing the ball unless it’s at 90-plus miles per hour towards a catcher, in which case he’s pretty good at it.

Lester’s inability to pick runners off with any kind of confidence has been well-documented. Most notable is the three-year stretch from 2012 to 2014 which culminated with the Royals running wild on Lester to come back and defeat Oakland in the 2014 AL Wild Card game. Despite finding ways to occasionally nab a runner at first – most notably after a profanity-laden pep talk from Willson Contreras last summer – Lester still has just three pickoffs in the past three seasons.

More relevant to this discussion is the fact that Lester had three intentional walks in 2017, the first time he had issued any since 2012. In fact, the veteran lefty has just seven IBBs in total over the 12 years, 348 starts, and 2184 1/3 innings of his major league career. In Lester’s case, clearly Joe Maddon did alter his decision-making process, knowing that he wouldn’t have to ask him to throw the four balls.

In the case of Boyd, Devenski, Norris, and Davies, none of them had reached even 200 career IP prior to 2017, so it’s hard to draw any real inferences from that kind of sample. After all, there were 82 pitchers in 2017 alone who pitched at least 50 innings and didn’t issue an intentional walk, from the exceptional (Chris Sale) to the forgettable (Jarlin Garcia). Sometimes pitchers are just going to get a little way into their careers before even being in a situation where they might have to issue an intentional walk, especially if they are pitching in lower-leverage situations or in the American League, as all of those pitchers but Davies have throughout their careers.

Lester aside, it’s hard to find examples of changing behaviour as a result of the new rules. What if we stop thinking in terms of managers and players and instead turn to a more fundamental underlying principle: the base/out state? Below is the total number of intentional walks by each of the base/out states (excluding bases loaded, a state in which there have only been seven IBBs in MLB history and none since Josh Hamilton received the treatment in 2008). The 2017 numbers have also been formatted with a colour scale from dark blue (biggest decrease) to bright red (increase) to indicate changes from 2016.
 

Intentional Walks by Base/Out State, 2015-2017

It does seem that managers were more willing to call for intentional walks with two outs and runners on second and/or third, although in most cases those totals were still below the 2015 levels. The opportunity to set up a double play without accidentally advancing the runner at second with one out also appears to have been slightly more tempting.

Most significant looks to be that walk which loads the bases with two outs. Not only did the 163 walks in that base/out state significantly top 2015 and 2016, it was the most since 2011, when there were also 163 in a year that featured over 250 more total intentional walks than 2017. One manager stood out as having a massive change in behaviour in these situations and he’s now without a job: Terry Collins, who issued just two intentional walks in that state in both 2015 and 2016, then spiked to a league-leading 12 in 2017.

It’s hard to believe that managers have been worrying about runners advancing and scoring in such situations but they clearly called for more walks. It’s less surprising to think about it in terms of the sabermetric wisdom on the situation: second and third with two outs is one of the few situations when the intentional walk does make sense, as long as that gulf in quality between the hitter at the plate and the hitter on deck is present.

That brings us to another possible explanation: that this is a function of a combination of the changing nature of league production and increasing acceptance of the principles laid out in places like The Book, rather than any particular managerial tendencies. There are now simply a lot more hitters who are a threat to hit a home run on a regular basis, and yet at the same time pitchers are worse than they’ve ever been at the plate. That’s not hyperbole: pitchers supplied a minus-20 wRC+ in 2017, the worst performance by the position in history. They slashed .125/.157/.163 and struck out in 38.4% of plate appearances.

If this is a significant driver, it should show up in the numbers in terms of how often the hitter in the eight-hole is getting intentionally walked, and it does. Number eight hitters were intentionally walked 220 times in 2017, up 35 walks on 2016, which itself was up 17 on 2015. More relevant, however, is the percentage of total intentional walks that were handed out to batters in that spot. Look at the red line below:
 

Eight-hole hitters made up almost a quarter of all intentional walks in 2017, with the largest share in the league and since the most recent round of expansion. That even undersells the point: it was actually the highest percentage since the DH was introduced in 1973, so for all intents and purposes, the highest ever. Why face the hitter at eight when you can face a pitcher with a .300 OPS at nine? This plays perfectly into the circumstances in which an intentional walk does make sense: pitchers are now so bad that the run expectancy is not adversely affected by loading the bases.

Whether the overall rise in intentional walks is a genuine change or simply a one-year outlier in an otherwise declining trend remains to be seen. The data makes the most sense in the context of a league of pitchers who are being left behind by an offensive revolution, of teams that are more stat-focused than ever, and of managers who are increasingly led by the information coming out of their front offices, rather than acting on their own instincts. While it’s fun to imagine that intentional walks surged because skippers were liberated from the stress of the incredibly rare wild intentional ball, it’s probably not true. There just aren’t many Jon Lesters out there.