2. Cody Bellinger
The only guy who is proven to play gold-glove-level first base defense at the big-league level is Cody Bellinger. And you know what, that's probably where he will play for the time being with Mike Tauchman emerging as a viable option in center field. However, I feel like it's only a matter of time before Tauchman's stats come back down to Earth. If/when they do, it will be hard to justify giving the 32-year-old journeyman playing time and there is good reason to keep his leash to be short.
When this happens, Bellinger will be moved back to center field (assuming the Cubs don't trade him at the deadline) leaving the hole at first base even bigger. Unless the Cubs plan on plugging center field with Christopher Morel, which seems possible given how little they've played him at third base, Bellinger could be staying at first for the rest of the season. If that happens, they better offer him a contract extension if he continues producing at the plate.