@Marc, heres the deal. United before SAF hasnt won a title for a long time, they were kinda like Liverpool now (a FA Cup here and there but 30something years without a title). After he left they again cant win the league or in Europe (they were in a CL final just 2 years before he left), and they had some big names as their managers, while spending 200M a summer. Us? We were successful before Trapp, he left and we still were successful, Lippi left and we again remained successful, Capello was somewhat successful, then Calciopoli happened but after we recovered we are again successful with 2 different coaches (we even finished 2nd and 3rd in the 1st 2 seasons we returned). Its not that hard to conclude that our success isnt dependant on who our coach is, unlike United.
And yes, UEFA Cup was underrated, before UEFA decided to make it a pathetic competition. You had Champions playing the Champions League, Cup winners the Cup winners Cup, and 2nd, 3rd etc placed teams in what is now the Europa League. Thats as if today we would have a competition with Arsenal, City, Tottenham, Real, Atletico, Sevilla, Monaco, Lyon, Napoli, Roma, Dortmund, Leverkusen, Porto all playing there, which would have been much stronger than it is currently. It was a strong competition, in some seasons even stronger than the CL, but ever since we have the top4 clubs go into the CL it has lost a lot of quality and apeal