Jackie Bradley Jr.'s recent success was bizarre

To date, Jackie Bradley Jr. has had a wild career. He was drafted 40th overall by the Red Sox in 2011, during his junior season at the University of South Carolina, and moved through the system quickly. He started 2012 at high-A Salem, and finished the year at AA Portland, snagging an invite to Major League camp for 2013 Spring Training. At that point, MLB.com ranked him as the 32nd best prospect (putting him behind only Xander Bogaerts among Red Sox), citing his advanced hit tool and plus defense in center field.

And that was before he hit .419/.507/.613 in Spring Training, and walked as often as he struck out, leading to him breaking camp as Boston's Opening Day left fielder. To be fair, the competition wasn't exactly stiff – the playing time not taken by JBJ would be covered by the somewhat-less-than-inspiring trio of Daniel Nava, Jonny Gomes, and Mike Carp –but it was still a remarkably rapid ascent for the 23-year-old outfielder.

Unfortunately, Bradley Jr. became yet another lesson in the unreliability of Spring Training performances, hitting for a 68 wRC+ with a 29.0 percent strikeout rate over 107 trips to the plate in his debut season. When he was demoted to AAA , however, he hit for an excellent 130 wRC+, so it seemed that he just needed some more time to develop. Then 2014 went even less well; Bradley Jr. would stay in the Majors for basically the whole year, but end with a putrid 46 wRC+ and a still-sky-high 28.6 percent strikeout rate.

He still ended up with 423 PAs, however, on the back of his glove, as the true magnitude of his defensive abilities finally became clear. By Baseball Prospectus's fielding metric, FRAA, he played 949 innings in center field, and was the fourth-most valuable non-catching fielder with 20.2 runs added (only behind Kyle Seager, Jean Segura, and Jason Heyward, all of whom had substantially more playing time than Bradley Jr.). That's how, even with his terrible season at the plate, JBJ still managed to be an above-replacement level player, garnering 0.5 fWAR and 0.8 WARP. This was the first iteration of Jackie Bradley Jr.: a terrible hitter barely able to justify his presence at the plate via incredible wizardry in the field.

Bradley Jr. began 2015 in the minors, but his 150 wRC+ made clear that, if he was going to fix his problems with major league pitching, facing minor league pitchers would not be of much help. Boston called him up on June 25, and while the fielding remained outstanding, suddenly the hitting was as well. In 255 PAs over the remainder of the season, JBJ's strikeout and walk rates improved only slightly from his terrible 2014. The improvement came via his isolated slugging (or ISO, SLG-AVG and a good measure of pure power), which shot up from a .084 across 2013 and 2014 to a .249 in 2015. ith a 250 PA minimum, Bradley Jr.'s ISO ranked 18th leaguewide, around names like Paul Goldschmidt (.249) and Yoenis Cespedes (.251), and he ended the season with a 121 wRC+. This was a new iteration; still outstanding defense, still lots of strikeouts, but a new ability to contribute offensively via prodigious power.

Much has been written about his emergence in 2015, trying to determine what caused it and whether it will carry over to 2016 and beyond. For the most part, these articles can be summed up with a  ¯\_(ツ)_/¯, and I'm not going to add any prognostication to the pile. Instead, I think it's worth recognizing just how weird Jackie Bradley Jr.'s 2015 skillset was.

There are 6,122 player-seasons with at least 250 PAs in the last 20 years, 1996–2015. Of those, 2,893 had a walk rate between 7.5 percent and 12.5 percent, and 261 of those also had a strikeout rate over 25.0 percent. FanGraphs' Def is a counting statistic, so I prorated it for each player-season to 600 PAs to get Def/600. Of the 261 remaining qualified seasons, only 18 had a Def/600 over 15.0, and only four of those seasons had an ISO over .200.

Even before getting into the list, I think it's important to note that none of these criteria are super exacting. 47% of the sample met the walk rate requirement; 8% met the strikeout rate requirement; 10% the Def/600; 24% the ISO. If these percentages were applied totally randomly to a sample of this size, you'd expect slightly more than four player-seasons – 47% * 8% * 10% * 24% * 6,211 = 5.7. Since ISO, walk rate, and strikeout rate are correlated, and wouldn't be applied randomly, that implies there's something odd about this skillset – probably that outstanding defense and prodigious power rarely go together.

More evidence that this is a strange mix of skills is that none of these players ever repeated this combination, despite the four of them having 24 seasons total in the sample. Most often, it was the defense that kept these players from qualifying in any of their other seasons – Rasmus was never again a plus fielder, Andrews never again reached the heights he did in 1996, and Cameron didn't reach the threshold in nine of his other thirteen seasons (though he was frequently good).

For what it's worth, the projection systems don't seem to think Bradley Jr. is likely to repeat, either. Steamer, ZiPS, and PECOTA all think his ISO will fall by roughly .100, though they also think his strikeout and walk rates will stay roughly the same. (That profile projects to roughly 2 WAR in something like 500 PAs.) If that happens, who are his comps? I kept the same requirements, but required the ISO to be between .125 and .175 instead of .200 or above.

Weirdly, despite more players in the sample as a whole having an ISO like Bradley Jr.'s projected one (31%), this skillset is even more rare. Prognosticating based on these comps is also basically impossible; the Russell and Castro seasons are both from last year, so there's no sense of where their career goes from here, and while Johnson played another eight seasons in the majors, as a catcher, his trajectory is probably of limited predictive value for JBJ. For whatever it's worth, however, he accumulated 14.2 fWAR over those eight seasons. Elite defensive value plus slightly less good offense than above is still a solid player.

Ultimately, however, projecting Bradley Jr.'s future based off his stats alone is a difficult endeavor. As Kiley McDaniel, then-FanGraphs' chief prospect analyst, wrote in response to a question about JBJ after the 2014 season,

It’s all about adjustments at the plate. Some guys do what JBJ did in the big leagues, then fix it and become what they should…and some never do.

JBJ made his first adjustment in 2015, selling out for power, and while it resulted in a productive season, it had consequences. As Jeff Sullivan noted in an article from last week at FanGraphs, Bradley Jr. had one of the largest gaps in run value between fastballs/cutters and softer pitches. As Jeff also noted, Bradley Jr.'s rate of hard pitches seen dropped 10 percentage points from 2014 to 2015, as pitchers adjusted to his adjustment. He's not the same player he was in 2014; he can't be the same player he was in 2015, or pitchers will take advantage of his predictability. For a player as young as him, we can guess at his skills, but not at how he'll deploy them. I can't say whether or how JBJ will succeed in the future, but the way he succeeded in 2015 (and is projected to succeed in 2016) is very weird.

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Henry Druschel is a Contributing Editor at Beyond the Box Score. You can follow him on Twitter at @henrydruschel.