Keenum has the 3rd worst current starting QB rating in the NFL at 75.4. Only Fitzpatrick and Osweiller are worse than Keenum.
You're not the worst offense in the NFL if your QB is any good. And that what the Rams are, 32nd.
Keenum is a laughing stock of a QB everywhere except with some Rams fans and Fisher. The Rams are trying to make the playoffs with an average backup QB and the rest of the team isn't good enough to carry him.