When Kang is healthy and focused, as he was at the end of last season and in 2015, he's proven to be much more than a platoon player. He can hit both left and right handed pitching.
Mercer and Harrison, with their fielding, are more than good enough at the defensively oriented positions of SS and 2B, IF the Pirates get good offensive production from the corners.
I'm just not quite as pessimistic about the infield as many people are. Kang and Bell both have 80+ RBI potential, IMO.
I actually think the offense overall will be fine. It's the pitching that is the question.
Cole, Taillon and Nova could actually be a very solid top 3, but the inability to acquire a legit #4 hurts. They're going to be a lot more dependent on Glasnow's development than one would like, but if the light does come on for that kid in additional to a rebound from Cole, the Pirates are going to surprise a lot of people in 2017.