Justin Bour was a bit of a revelation for the Miami Marlins in 2015, picking up the full time gig after Michael Morse was moved at the trading deadline last season. Bour ended up putting in a respectable .262/.372/.429 slash line and belting 23 home runs while driving in 73 in 446 at bats, finishing fifth in NL Rookie of the Year voting.
Yet most of Bour's damage at the plate came against right-handed pitchers. In fact, despite showing good power to all parts of the field and the ability to cover a large portion of the plate with his swing, none of his home runs came against left-handed pitching. Indeed, in the admittedly small sample size of 75 plate appearances, Bour put up an unsightly line of .221/.293/.279.
Thus, the consensus around baseball and in the Marlins' front office might be that Bour is probably going to need a platoon partner going forward. Some have been vocal proponents for the likes of Steve Pearce, a right-handed first baseman/outfielder most recently with the Orioles. Pearce struggled in 2015 but was excellent the year prior, putting up a 4.9(!) WAR in a part time role. The 32-year old remains a free agent, however, because the Marlins found another guy they liked in Chris Johnson.
Marlins fans might remember Johnson for his role in the 2013 scuffle with the Braves, but aside from that he's a right-handed hitting first/third baseman who is entering his eighth season of professional ball, having played for the Astros, Diamondbacks, Braves and Indians. Johnson has put up a .314/.350/.436 career slash line against left-handed hitters, so unless the tank is empty at 31, there is reason to suspect he can be an effective if light-hitting half of a first base platoon. On the surface of things, that appears to be the Marlins' plan.
I confess that I came into this article with the mindset that I was going to find something to show that Bour didn't need to be platooned, and as you can guess, much of the evidence points to the contrary. There is, however, hope that he can improve against lefties and become a more complete hitter. An example of such arose in the NL East amongst the defending National League Champions.
Entering 2015, the New York Mets had questions as to whether or not to platoon first baseman Lucas Duda. Much like Bour this past season, Duda had been excellent against right-handers, but had shown nothing in the minors or majors to indicate he could be effective against left-handed pitchers, and indeed, had been downright deplorable in 2014 against them. The Mets went as far as to sign Michael Cuddyer to, in part, potentially act as his platoon partner. You know what happened next, but here's a nifty table illustrating Duda's transformation all the same:
*PA = Plate Appearances
The Mets essentially gave Duda the same number of at bats, despite his struggles the previous season, and he came through in a big way. That meteoric rise in slugging percentage was undoubtedly helped by Duda bashing seven home runs off of left-handers last season.
Now, you might be thinking, "120-130 plate appearances? That's not much of a sample size." For context, there were 95 left-handed or switch-hitting batters in 2015 with at least 50 plate appearances versus left-handed pitching and Duda checked in a little more than halfway down the list at No. 48. Indeed, there were only 15 swinging southpaws in the game who had 200 or more plate appearances against their left slinging comrades on the mound.
I'm not saying that Bour would turn out the same given the opportunity, but the Mets gave it a shot and Duda emerged as an everyday player for them. Justin Bour is entering his theoretical prime at age 28, the fences are coming in, and that Barry Bonds fellow might know a little bit about lefties crushing lefties. Don't be surprised if the anticipated "strict" platoon isn't so strict at all.