The "power" will come for Kepley. He only needs to hit 5-10 HR. Kwan was a 3 war player with a 5 HR season and damn near a 5 win player with 6 in his rookie season. I expect Kepley would provide more bsr and potentially defensive value as well. The height is less of a concern these days. Freaking Frelick managed a 115 last year and was 3.5. Pretty similar to Kepley as a prospect, Offensively.
IDK, I'm overzealous, and he will almost certainly never take an AB as a Cub but this dude has just about a half seasons worth of PA as a pro and has:
15 XBH, 30 SB, 54:31 BBK, 15 HBP, 2 GDP, ludicrous LD rates with really low GB. He's a dirtbag and a really fun player to root for.