Par4QC Still trying to grasp this. Possibly 1 of the worst QBs I've seen in the past few years.
It seems that contract extensions for QBs follow a pattern - an above-average starting QB will normally get a 4-6 year contract in the range of just under to just over the current highest annual average value for a QB contract. (By 'above average starting QB', I mean players like Kirk Cousins, Derek Carr, Jimmy Garoppollo - guys who can run the offence competently, but are unlikely to carry the team further than the talent around them will take it.) Next offseason will be interesting, as it's likely that Joe Burrow and Justin Herbert will be looking for contract extensions, and these are likely to be at least at the current top of the market (as the salary cap is expected to rise significantly over the next few years).
Murray isn't a great QB, yes, but he's shown that he can make plays, whether that's throwing or running. He does seem to be injury-prone, though, which is probably the biggest concern.