JQT, coming back from a bad injury is always a risky time for club and player. Robshaw and Lambo managed it, Jonny Wilkinson and Manu Tuilagi managed it eventually, Lawrence Dallaglio managed it by coming back a very different player, Ross Chisholm came back a diminished one, George Lowe and Will Skinner didn't manage it at all.
Sometimes it works, sometimes it doesn't. One of the big factors in recovery is how the player approaches it, and their own club is generally best placed to judge that. But it's hard to tell if the injury will hold up.
That said, we used to be really good at rehabilitating players, and able to take a chance on other teams' crocks. Ollie Kohn was coming back from a knee reconstruction when he joined Quins, and we took him from a journeyman with a bad injury record to an international with a career-ending injury record (thanks, Wozza).