I think guessing as to when and what Karlsson should've done with his injury is a moot point. We don't know nearly enough details to suggest medical procedures. He could've tweaked it and then really hurt it later. The doctors could've suggested no surgery at first, but then changed their minds. He may have fallen out of bed the night before the Blues game and landed, groin first, into his box of hipster shaving gear and torn it much worse.
Point is, we don't know anything, so it's silly to be angry/suggest what the appropriate treatment should've been,