It's a bit of a moot point, Cali.
The likes of O'Neill and Moyes probably would have "what it takes" given an opportunity and backing to manage a club that regularly qualifies for the Champions League and do a reasonable job.
However, they would need to be supported by top class scouting networks, they would need to innovate tactically to prosper in European competition and they would need to get used to just how thinly spread squads get when they're still competing seriously on four fronts as the run-in starts.
In short, while they may have, and may have always had the aptitude, they lack the experience, and it's by now becoming rather late for them to acquire it.
When Arsenal started to play regularly in the Champions League under Wenger, it was several seasons before we started to consistently get out of the group stage. We struggled with late away draws and losses for some years, and it's European competition (as well as the players we had available) that has led to us abandoning 4-4-2, rotating more etc.
