So, Jackie Bradley Jr. hit another home run last night. It’s his seventh of the season and his sixth since May 5. That’s six home runs in 13 games to go with a .404/.474/.762 line. All the while, he extended his hitting streak to 24 games. It’s pretty crazy. He’s on a tear, for sure.

But I’ve seen some overenthusiastic Tweets about his breakout being legitimate. That, I don’t fully understand. He doesn’t seem like a fundamentally different hitter than the JBJ we saw in 2013. Or 2014. Or 2015.

Obviously, the .271 ISO (isolated power) is impressive for a relatively tiny dude. It’s not far off his .249 ISO from last year, so it looks like it might be something sustainable. His strikeout rate (K%) is way down, too, which is undoubtedly a boon to his triple-slash line. But red flags abound with JBJ, all (or most) of which I will detail here.

This isn’t the first time JBJ has done something like this. Last summer, Matthew Kory recognized that JBJ was running similarly hot. For the lazy-fingered, here’s some visual evidence for your viewing pleasure:

The point at which an obviously very talented graphic artist wrote then is approximately when Kory wrote his piece on JBJ; the point at which the same obviously very talented graphic artist wrote now is, well, now. (As of yesterday, at least.) Note the peaks and valleys here. JBJ has streaked in big ways, but he has also predictably cooled down, not unlike he should be expected to do soon.

I haven’t given JBJ an overwhelming amount of credit yet, but take a look at the reference (dashed) line above. It represents JBJ’s wOBA during the duration depicted above (2015-16). It’s a wOBA that, among hitters with at least 400 plate appearances since the beginning of 2015, ranks among the top-20 in baseball. That’s no minor feat — he’s sandwiched between Ryan Braun and Edwin Encarnacion, and he trails only the game’s most prodigious sluggers.

That’s obviously incredible. I won’t deny it. But let’s get to the red flags. Foremost, his .378 wOBA since 2015 is fueled largely by a .344 batting average on balls in play (BABIP). That’s not unreasonable in itself. But his career BABIP currently sits at .306. Now, JBJ hits the ball hard, which, as aforementioned, is impressive for a smaller hitter, and he’s got wheels. Those, and a nice hard-hit rate (Hard%), can be enough to propel a hitter to an above-average BABIP. His current .390 clip is unsustainable, but maybe he can pull off, I don’t know, something like .340? .350?

Except all this newfangled Statcast data can’t validate JBJ. Andrew Perpetua’s expected BABIP (xBABIP) equation pegs JBJ for a .307 xBABIP. Now, I love that we’re already getting places with the Statcast data, but (1) it’s not necessarily predictive, and (2) it doesn’t account for a player’s speed. JBJ is a fast dude, and maybe his Statcast xBABIP is underselling him.

My xBABIP equation, which incorporates a hitter’s speed score (Spd) — not a perfect metric, but it’ll do, pig, it’ll do — pegs JBJ for a .367 xBABIP. That’s quite a bit better. But it’s not like JBJ suddenly got quicker. With that said, JBJ only posted a .287 BABIP through his first 785 career PAs despite quality contact and superb wheels. What makes us think he’ll be substantially better when relying on largely the same skill set and batted ball profile?

Moreover, I can’t say for certain which xBABIP equation is “better.” I think they both have their merits, but the Statcast equation (currently in a black box) could be quite a bit better. Unfortunately, we can’t know for sure (not yet, at least). Let’s give JBJ the benefit of the doubt, split the difference between them, and appoint him a .337 xBABIP. That cuts into his batting average at least 30 points.

That’s before the plate discipline issues. What issues?, you ask. His strikeout rate is almost 7 percentage points lower than his 2015 rate.

JBJ is, right now, his most aggressive self. His swing rates of 67.6% in the zone, 30.1% out of the zone, and 47.3% overall all represent career highs. Fortunately for him, he’s making the most contact on pitches outside the zone, offsetting his aggression. But he’s still sitting on an 11.6% swinging strike rate (SwStr%), almost identical to the rate he has maintained his entire career — a career during which, prior to 2016, he posted a strikeout rate north of 27%. There’s reason to believe he’ll continue to shave off the strikeouts as he matures as a hitter, but the peripherals point to maybe, maybe, a one- or two-point gain. Not a six-point gain.

Also, the aggression on pitches out of the zone hasn’t really paid off all that well:

Not only that, but we see that JBJ has basically feasted on only meaty pitches. As he should. But the additional swings on bad pitches aren’t helping his game, is my point. Those are the kinds of adjustments that prove less beneficial than superfluous.

Lastly, JBJ’s batted ball profile leaves me a bit puzzled. In discrete seasons, JBJ has posted incredible HR/FB rates in three seasons and a miserable rate in one. And that one, in which he posted a 1.1% HR/FB, was his longest-tenured single season. So, despite three separate stints of above-average power, his career HR/FB rate clocks in at only 10.3%.

His 38.9% hard-hit rate this year points to good things. But hard hits ebb and flow, and there’s a better-than-good chance that number falls a few ticks. Still, with a career rate around 34%, JBJ’s good for something like a 15% HR/FB. But with a career-low fly ball rate (FB%), his HR/FB ratio matters less and less.

So, let’s recap. Assuming JBJ has improved during his professional career, perhaps we can assume his career batting line is a safe baseline: 14 home runs, 10 stolen bases, and a .240-.250 hitter. If he’s truly the hitting maven he appears to be, his contemporaneous ceiling looks more like a 20-homer, 10-steal, .270-.280 hitter. That’s pretty sweet. I would be lying if that wasn’t pretty sweet.

But the red flags point more to the former than the latter. Maybe some of the issues I outlined above are not issues at all. Maybe JBJ ends up somewhere between those outcomes — with sub-par power but a good batting average, or moderate power with a sub-par batting average. Maybe I’m splitting hairs, but the ceiling is potentially a top-30 outfielder whereas the baseline is merely deep mixed or AL-only fodder.

Here I am, not coming to concrete conclusions. That’s not typically my intent. But JBJ, through four seasons, is still a small sample — not yet 1,000 PAs. He’s a veteran that, to an extent, is still a somewhat unknown quantity.

I do have a stance, though: I’m hopping off the JBJ train, especially before he inevitably comes down from his BABIP high. It’s not that I dislike(d) him or anything. He’s certainly an above-average ballplayer and a useful fantasy commodity in select scenarios. I’m more than happy to let him prove me wrong; besides, not everyone can string together 24-game hitting streaks. But, as of now, his current peripherals don’t point to any significant improvements or underlying changes that warrant undue optimism.