There's some logic in the reasoning for seeing Gruden as a risk, but in the end, I don't think it is valid.
First of all, the short term returns are going to be huge. There is no doubt that he would sell a ton of tickets this off-season and the hype behind the program would be huge. He'd pump a ton of money into the program right away. With most everyone else, the fan base would have a "wait and see" attitude.
I also think that the same hype would help recruiting in the short term. He would draw players early because he's Jon Gruden. He's one of the most recognized names in football on day one.
His name isn't going to carry him forever. But, I also think there's plenty of evidence out there that he is a strong football mind. He knows the game and can coach. His NFL resume should be enough evidence for that. So, if he has as much or more talent than every team he plays, he should win.
Once the program starts winning again, recruiting gets a lot easier. I know that Alabama works hard at recruiting, but it's also true that their success has them on autopilot to some degree. Guys who are offered there, usually take it. We can get back to that point with a few strong years of winning.
This program needs a big jump start back into relevancy. I don't think Gruden is the only answer to long term success, but he does put the program back in the spotlight on day one, and he has the resume to be successful.