I've not looked into it, but since his injury, how many minutes / games / consecutive games has he been involved in?
We've had players in the past coming back from injury who needed a good run of games before they got their mojo back (whether that be physical / mental or other).
I remember Vellacott being involved in some games, then I remember porter and wusty getting some game time too, but I don't recall how many games he got, whether he was starting regularly or how many games in a row he got
As said above, there's also an argument for how well the team as a whole were performing at that time too.
We had comments last week that our lack of direction wasn't necessarily the fault of the fly half because he was getting slow service from the 9.
Also, the 9 was being pressured because we didn't have our best back row available etc.
I don't know anything about scrum half play, and I can't remember what our performances were like with Vellacott playing, but I wouldn't be so ready to ditch him based on a few games immediately post injury