Pretty much agree with this, a top manager doesn't have the kind of career Wenger has had, the players he signed and inherited really made him look a better manager than he was.
I actually would describe him as a glorified scout, was very good at finding players on the cheap when scouting networks weren't as widespread, but nowadays that seems to have largley disappeared as well. His record before he arrived was hardly anything amazing, no doubt he did a good job with his limited skills in his first few years, but his weaknesses have been horribly exposed by superior managers for the last 12 years.
If he was a great manager he'd have won the CL and wouldn't have gone 12 years without a title, he also certainly would have been more competitive in the big competitions.
People hailed the stadium move he was championing (although it wasn't his money he was risking of course) as something great, it's proved to be somewhat of a disaster, since then we've gone backwards and turned into a club few fans would have ever wanted to see us transformed into, I miss those Higbury days, since the move to the new Stadium things just have never been the same.