Of course not, it was called Rex for a reason. Ray was the one that found the holes in the rulebook and told Rex what to build essentially. Hendrick pushed for an engineering department that other teams fell short on, and with Ray telling them what parts of the car to design and what to aim for, it led them to unparalleled cars on the track. The T-Rex car is what led NASCAR to make a much tighter rulebook, essentially making things more "spec" than ever before, and that's why you couldn't build anymore of those type cars (Ray tried with the Dodges at Daytona and NASCAR penalized them).
Ray had his own share in a team yes, but was not a crew chief nor did he have the engineering department that matched what he had at Hendrick. To say Evernham wasn't a vital part of Gordon's career is more of an insult to Gordon than it is to Evernham. It would also be like already mentioned Knaus with Jimmie Rustler Johnson.
Those two crew chiefs are probably two of the best we will ever see in the sport, turning their above average talent of drivers into legends. You can't be a true Gordon fan if you can't appreciate what Evernham did for him, simple as that.