Yet it's not as simple as it looks. Bruce is actually not hitting the ball harder than he did last year, as his average exit velocity has dropped from 90.5 mph to 89.4 mph. His overall launch angle is different by less than a degree, which is negligible. Bruce is striking out less than he has since 2009, but he's also walking less than he has. So what is it? Let's put out a theory: It's about being healthy, and about using the whole field.
Bruce has always been something of a pull hitter (just look at this spray chart of his home runs since 2012), but he'd managed to have success to the opposite field, too. For example, in 2013, he hit .396 with a .694 slugging percentage when going to the left side. Yet in the aftermath of his 2014 knee surgery, that skill was largely lost. Bruce hit .254/.313 to left field that year, and .242/.374 in 2015. (His numbers right up the middle followed the same trajectory.) Meanwhile, his pull power numbers were largely unaffected; he's slugged between .700 and .800 on pulled balls each of the past four seasons.
Opposing teams follow these trends, of course, and they reacted. In 2013, Bruce saw shifts when he put the ball in play 133 times. So far this year, with a third of the season yet to play, that's already up to 224 times, or nearly 81 percent. Even just last year, it was only 55 percent. (Obviously, all of baseball has seen a huge shift increase each year, which also matters.)
So what the Reds had was a player who was unable to do damage going the other way, and facing increasing numbers of fielders on his pull side. That shouldn't affect his ability to hit for extra bases that way -- and it didn't, that much, as we showed with the consistent pull slugging percentage -- but it would seem likely to limit his ability to pile up singles. Indeed, it did, because Bruce's pull batting average has dropped literally every year, from a high of .447 in 2012 to a low of .348 this year.
Back in May, Bruce talked to MLB.com's Anthony Castrovince about his season, seeming to indicate that the issues started with his injury. "I just feel stronger," Bruce said. "I hit a lot of balls on the ground the past two years, and I usually don't do that too, too much. I think in 2014, it had something to do with my knee. And I think in 2015, the bad habits I had carried over. So it's just fixing that."
Bruce is half right, anyway, because he's hitting the exact same amount of balls on the ground this year as he did last year. But the opposite-field production is back, in a big way. Let's adapt a table from a study that appeared on our partner site FanGraphs back in February, about how much Bruce's opposite-field production had fallen apart. The "wRC+" stands for Weighted Runs Created Plus, a widely-accepted advanced offensive stat that accounts for park effects and sets league average at "100."
Largest wRC+ declines in opposite-field production, from 2012-13 to 2014-15
1. Bruce -114 points
2. Jean Segura -112 points
3. David Wright -101 points
4. Torii Hunter -90 points
5. Melky Cabrera -82 points
What that's saying is that in 2012-13, Bruce was 67 percentage points above league average going the opposite way (a 167 wRC+), and in 2014-15, he was 47 points below average (a 53 wRC+). Combine those two numbers, and you get the 114 point drop that was larger than anybody else. A lot of those names made sense, anyway. Wright and Cabrera were dealing with well-publicized issues of their own, Segura was in the process of losing his job as Milwaukee's shortstop, and Hunter was at the tail end of a long career. Bruce's knee injury would qualify.
Now, let's run the exact same table, looking at largest increases in opposite-field production from the last two seasons to now.
Largest wRC+ increases in opposite-field production, from 2014-15 to 2016
1. David Freese +210 points
2. Gregory Polanco +182 points
3. Ian Desmond +151 points
4. Bruce +133 points
5. Wilson Ramos +127
That's a fun list, isn't it? Desmond's rebirth in Texas has been well-chronicled, and Ramos has been baseball's best-hitting catcher this year thanks in part to improved eyesight. And there's Bruce, who has two homers to left this year (he did so just once in 2014-15), and nine doubles that way, after eight the past two years. Suddenly, Bruce is producing to left just like he did before the knee injury. He's still hitting for power to right field. Combine that, and you get a slugger.
We know that the knee, and ensuing bad habits, were bothering Bruce for a while. We know that earlier this year, he was working with coaches to adjust his hands to make better contact on the outside of the plate and "to not [get] away from my strengths, which is driving the ball all over the field," as he told Mark Sheldon of Reds.com.
Maybe it's really that simple. It's certainly not all that satisfying of an answer, because when we see big changes in production, we like to have big answers. It doesn't always work like that, though. This isn't really a "new" Bruce, after all. It just looks a lot more like the old one. That's what interested suitors will be telling themselves, anyway.