Cody Bellinger is 21 years old, and he has been one of the very best players on the team that had MLB's highest Opening Day payroll. Bellinger is also the easy favorite to end up as the National League Rookie of the Year. It's worth noting that this isn't what the Dodgers envisioned for Bellinger.
Bellinger only got promoted in April because both Joc Pederson and Franklin Gutierrez were injured. The team said that when both those players were back, Bellinger would return to Triple-A. But Bellinger hit, and he didn't stop hitting. Pretty soon, Adrian Gonzalez had to go on the disabled list. Then Andrew Toles went on the DL. Then Gonzalez went on the DL a second time. And now Bellinger isn't going anywhere.
A short-term promotion has turned into a Rookie of the Year favorite who has played both first base and left field. Bellinger, at 21, has already started 17 games batting cleanup. And while Bellinger was initially supposed to be protected against tough southpaws, he has been one of the best lefty-on-lefty hitters in baseball, hitting even better (1.015 OPS through Sunday) than he has against righties (.944). This, in short, has gone as well as it could have gone.
Even though he got a late start to his season, Bellinger is tied for second in all of baseball in home runs with 21 after clouting two on Monday night. His dad, Clay, played 183 games in the majors, going deep a dozen times; Cody eclipsed that total in his 43rd career game. See, Cody is built to slug -- he owns baseball's ninth-lowest ground ball rate at 31 percent. To turn it around, he owns baseball's eighth-highest fly ball rate at 49 percent. Let's focus on those fly balls to understand something that Bellinger does particularly well.
What's the best possible result of a fly ball? That's easy -- a home run. What's the worst possible result of a fly ball? Well, any out, I guess, but specifically, popouts are the worst. They're effectively just strikeouts. A popup is nowhere close to being a homer. Home runs are great indicators. Popups are not.
This is a plot of two rates, both with fly balls as the denominator. On one axis, you see current rates of home runs per fly ball. On the other, you see current rates of popups per fly ball. I've highlighted Cody Bellinger in yellow.
The best place for any hitter to be is in the upper left. There, you've got plenty of homers and few easy outs. Bellinger finds himself in the right area, with a homer/fly ball rate of 32 percent and a popup/fly ball rate a hair under 7 percent. For Bellinger, the difference between the two rates equals 25 percent. That's the third-highest mark in baseball, behind only Aaron Judge and Eric Thames; their slugging feats this season need little introduction at this point.
We can take this a little bit further. The plot above shows that Bellinger makes excellent use of his fly balls. I've also already noted that Bellinger is a pretty extreme fly ball hitter. So, another plot. On one axis, you see fly ball rates. On the other axis, the differences between home runs per fly ball (HR/FB) and infield popups per fly ball (IF/FB). That's the stat where Bellinger comes out at 25 percent. Take a peek!
This time around, it's good to be over in the upper-right-hand side. Those hitters hit a lot of fly balls, and they also hit them well. Bellinger, again, is in yellow, and Bellinger, again, is in a great spot. He hits fly balls at the same clip as guys like Kris Bryant, Jay Bruce and Curtis Granderson, but Bellinger's fly balls have been easily the best in terms of how far they go and the impact they have (especially on the scoreboard). Basically, he's been making the most of a strength.
Whom might Bellinger most resemble? This is where we can have a lot of fun. If you ask Bellinger, he'd probably tell you he just wants to be himself. But it can be useful to consider player comparisons, because they help to anchor your expectations. For Bellinger, I have one comparison in mind.
Stay with me; this could get complicated, but I'll try to go as quickly as possible. Hitters, I think, have four pretty "sticky" traits. That is, traits that are closely related to their identity as hitters. There's plate discipline, and there's the ability to make contact. Then there's also contact quality. That can be further split into batted-ball speed and batted-ball trajectory.
To measure plate discipline, I like to look at the difference between a guy's in-zone swing rate and his out-of-zone swing rate. To measure contact, there's contact rate out of all swing attempts. Then Statcast comes in handy for the other stuff. For batted-ball speed, there's average exit velocity. And for trajectory, there's average launch angle.
To get this info, Statcast information can be easily accessed at Baseball Savant. Statcast information exists going back to 2015. So, I looked at the last two-and-a-half years of data, for all four statistical categories. I ran some simple math to look for the hitters most comparable to Bellinger. I'll show you a table. You've got Bellinger, and Bellinger's closest 2015-2017 statistical comp.
Most of this should be familiar, but Z-Swing percentage minus O-Swing percentage is the difference between a player's in-zone swing rate and out-of-zone swing rate. By all four measures, Bellinger, to this point, looks a lot like recent Chris Davis. And recent Davis has been more or less the same as whole-career Davis.
Davis, obviously, is much older, but he's a lefty who stands 6-foot-3. Bellinger is a lefty listed at 6-foot-4. Both players feature mammoth power with something of a strikeout problem -- Bellinger has struck out in 31 percent of his plate appearances, and Davis is at 32 percent for his career. Like Bellinger, Davis has made several defensive appearances in the outfield. Davis debuted a little after his 22nd birthday, while Bellinger debuted a little before his.
Over the course of the past decade, Davis ranks third in baseball in home runs per fly ball. In terms of the difference between home runs and popups per fly ball, Davis ranks second. He has been an inconsistent (but overall productive) hitter, and you could argue that comp for Bellinger is a wee bit conservative. Cody Bellinger looks like Chris Davis -- but he's young enough to become even better.
So, one immediate takeaway: Bellinger already looks a lot like a guy the Orioles have valued highly after he crushed 159 home runs across four seasons, leading MLB in 2013 and 2015, giving him a seven-year, $161 million deal to re-sign with Baltimore after 2015. Davis has made an All-Star Game, and he has twice garnered MVP support. Chris Davis has a career slugging percentage of .497.
That's how good Bellinger has been -- he already resembles a guy who put up 53- and 47-homer seasons. But Bellinger doesn't turn 22 for another few weeks, and he seems quicker and more athletic than Davis. Bellinger could ultimately be the more valuable defensive player, and it's conceivable he adjusts over time to cover spots in the strike zone where he doesn't do as much damage. Davis has always struck out; Bellinger could work to eliminate a few whiffs, giving him the chance to send even more batted balls in the air and possibly be even better than one of the best sluggers the game has seen in recent seasons.
You can see why Bellinger is on course to win at least one trophy -- as his league's best rookie. You can see why he has so many Dodgers people excited. It's true that Bellinger doesn't always make contact, but when he does, few players in baseball are better at doing damage at the plate. That's not too shabby for a guy who wasn't even supposed to be major league regular yet. Sometimes, the best players set their own schedule for when they'll be ready for The Show.