I've never seen any of these guys play but your Walker-Balboni comparison caught my eye. So I did some digging on bbref (time on my hands tonight). Assuming Walker starts 2015 in AA, both Steve Balboni and Adam Walker will have begun their first season at AA at age 23. Balboni was in the Yankees system in the early 1980s so these are just general comparisons. Balboni was coming off his age 22 season at A with 584 PA, 26 HR (4.5%) with BB-SO totals of 69-154 (rates of 11.8% and 26.3%) and a .798 OPS. Walker's age 22 season at Fort Myers last year was 555 PA, 25 HR (4.5%) with BB-SO totals of 44-156 (rates of 8.0% and 28.1%) and a .743 OPS. Both are fine; Balboni wins by half a length. However, Balboni's AA season he made nice progress, increasing his walk rate up to 13.4%, increased his HR totals and rate, and hitting for a .301 average and .951 OPS. So these are the numbers Walker will need to post at Chattanooga to keep pace with Balboni. Balboni then spent the next couple seasons back and forth between AAA and MLB before he was traded to the Royals, who as it turns out had a use for him (for all his flaws) in their already very good lineup. The point of all of this is to say that, if "Walker's plate discipline doesn't improve, his ceiling will be Steve Balboni" might be amended to say if Walker's plate discipline finally does improve, then his ceiling will be Balboni. And in further comparison, Balboni's minor league production lagged behind other "all-or-nothing" power type guys I checked, like Jay Buhner and Adam Dunn. So, Walker has a lot of work to do, but I've heard good things about him so am of course pulling for him.