Scooter Gennett is very bad at hitting left-handed pitching. In his major league career to-date, he has hit just .128/.150/.141 in just 83 plate appearances against southpaws as the Brewers have sought to protect their second baseman from facing lefties.
That is a small sample size, certainly, but keep in mind that Gennett also OPS'd .667, .607, and .592 against left-handers in his last three minor league seasons. Simply put, Gennett is very bad at hitting against lefties.
For that reason, Rickie Weeks was kept hanging around (and also because Weeks was being paid a large amount of money and was hitting pretty well). Weeks won't be around next year because the Brewers won't be willing to give him another large amount of money. As such, Gennett will be listlessly floating by himself in at-bats against left-handers.
Or will he? Though Weeks is gone, that doesn't mean that other options don't exist. In fact, there are a few free agent options on the market that could be intriguing platoon-mates for Gennett. Among them are players like Emilio Bonifacio (career .721 OPS against lefties) and Brian Roberts (.714 but better against righties), both of whom would likely come cheap. Other options that may be a bit more expensive include Asdrubal Cabrera (.751) and Jed Lowrie (.776).
Of those, the two most appealing are likely Bonifacio and Lowrie. Bonifacio comes with the added benefit of being able to play nearly anywhere on the diamond, giving flexibility on the bench. Lowrie has some nice power and has played shortstop, providing insurance there. Roberts, if he continues to play, is fragile as anyone and Cabrera has had a rough last two seasons.
As far as internal options go, the switch-hitting Elian Herrera is perhaps the best candidate to platoon. However, there's little guarantee he would hit better against lefties than Gennett over extended time. There's no way I trust Luis Jimenez or Hector Gomez to pick up a significant share of playing time at the beginning of the season.
The Brewers are going to have to ask themselves what they see as the future of second base at some point. Will they keep a platoon going for another five years, or will they eventually allow Gennett to stand on his own against pitchers of all handedness? Obviously much of that will depend on how Gennett plays. If he can hold his own when playing against lefties, it will go a long way toward establishing his value moving forward.
Of course, the one benefit to not platooning Gennett is that it would allow a bit more flexibility on the bench. In 2014, whoever didn't play between Weeks and Gennett was useless except as a pinch-hitter. Having another spot they can use could allow Milwaukee to shore up a bench that was a clear weak spot last year. It's also not outside the realm of possibility that the Brewers end up with another platoon at first base, taking away another potential bench spot. That said, someone like Bonifacio could provide the best of both worlds: Flexibility while giving a platoon option at second base.
But then, thinking about the bench before part of the team's starting production is putting the cart before the horse a bit. I complained a lot about the bench in 2014. I'd have complained less if I were instead griping about another (after first base) starting position that had a clear path of improvement.
First base will obviously be the biggest concern for the Brewers this offseason. After that, they'll have to see what kind of budget remains. With enough left, we could see a new platoon-mate for Gennett in 2015.