I think the holdup was maybe a little hesitation over his temper and ability to stay out of trouble. Not too many strikers pick up as many fouls as he does. But he's really gotten that aspect of his game under control.
Probably some of the math had to gel, too. Almost all of the big names have moved, so now it's the tier just below them getting sorted out. Taty's in that group, Saša Kalajdžić from VfB Stuttgart (my Bundesliga squad), dudes like that. The last pieces of the puzzle.
So, yeah. He's gone this window. Maybe he's gone already and they just have to finalize the paperwork. It sure looked that way when he came off today.