The pen's general flakiness is really exaggerated by their failings in just a few games. We can't ignore those games and pretend they never happened, but there have been plenty of examples of the bullpen's success.
We have a decent core in the pen, but I think Kimbrel's chances are running out, and if he doesn't have it, he needs to go somewhere or lose his closer spot and get relegated to a cleanup man. Better to have Cano just close the 9th than to watch Kimbrel almost blow it, then have Cano come in to bail him out.