Toolsy would be a great nickname for a baseball player.
I still don't really think Hays is a major piece moving forward. Passable starting corner OF, maybe closer to average, and can fill in for you at CF which gives you a lot of roster flexibility in not needing to carry a glove-only reserve OF. I admittedly didn't watch much over the final months of the season, so maybe he made some improvements in approach, but beyond the health I think his biggest concern is his approach at the plate. Not just the low walk rate, that's a symptom, but the root cause is the aggressive guess-only swinging. I don't think he can overcome that often enough to have really good overall numbers and I've never seen any hint of change or improvement from him in that regard.
Worst case is he's a good bench player, he can fill in at all 3 positions, has speed and pop. I think he is better than even that, but I don't see very good odds of him being better than a mid-tier or lower end starter. He'll be the guy next year though, so he'll get another opportunity to improve upon what we've seen to date.