We can tell a bit from Social Media though, the players who are seen interacting with each other, training ground footage, comments in interviews etc. Of course its picking through propaganda, but there's enough there to get a general feel that Zlatan had a positive impact in the dressing room, in the same way there's enough to understand Sanchez didn't click at united.
Calling him a mediocre footballer is a bit of a miss IMO, he's obviously not as good as he was 10 years ago, but he showed more than enough when he was with us to show that even with a couple of years drop off he can still hold his own and make a decent impact for half an hour at the end of a Prem game.
Yes I agree plan A needs to massively improve, but to say we don't need a plan B is absolute fantasy. Unless you're absolute world class, you need a plan B. Utd always had one under Fergie. Upront Sherringham/Ole were different players to Yorke/Cole, and Rooney/Berbatov/Tevez weren't all the same. Behind them we'd play Nani for the creativity, but switch out for Park when his industriousness was more valuable and time on the ball would be limited. Sure lumping it up to the big man isn't a pretty tactic, but its worth having in the bank if a defence is playing exceptional at shutting down passing space and blocking off the runs - and it's not like Zlatan or Mario are donkeys with the ball at the feet.
The truth is, were not City/Liverpool, and can't stick to our game because it'll always win out - we've seen so much this season lesser teams can nullify it quite well if we aren't at our sharpest. We are not going to massively, massively improve that plan A in the winter window, so getting something different for cheap can't be a bad thing for the interim. It's not like we'll be blowing our budget on it and sacrificing signings in other positions, and I doubt were struggling for spaces in our PL squad given the number of youngsters we are using. It just seems, well, prudent, to throw something different into the mix