Although many writers have voiced concern that Chelsea would merely buy both EPL and European championships, a few lessons come out of their dismantling by Barcelona.
1. The composition of teams needed to win domestic championships are not perfectly correlated with those needed to win shorter competitions. The deep, player-in-player-out squad that helps Chelsea dominate the league may actually hinder them when playing against equals or near equals. The situation is not unlike the Atlanta Braves -- good to very good and deep starting pitching dominated the divisions over 162 games for many seasons, but in a 5 or 7 game post-season, a small number of great starters, timely hitting, and some luck make the difference. In other words, one cannot rely on the law of large numbers in small number situations.
2. Chelsea is not Porto. Jose Mourinho took Portugal's Porto -- a very good club but not among Europe's elite in terms of cash -- to the European title with a very conservative strategy. Often, that is portrayed as "the way" to win in Europe. He's now gone with the same strategy for two years at Chelsea to be knocked out Barcelona while scoring 2 goals in 2 games this year and scoring none against Liverpool in two games last season. Unlike Porto, Chelsea has the stallions to win games scoring 3 or 4 goals -- last year's thrilling comeback against Barcelona in the second leg was an indication. The same coaches who are great against better teams are not always as great against equals, especially when their strategy and tactics are inflexible. A highly conservative style benefits teams with lesser talent. As John Wooden said, "I learned that I had to either adapt or fail."
3. Dollars matter but so does management in sport -- whether at the owner, GM, or coach level. Yes, Chelsea's dollars make them a cinch against the likes of Sunderland -- probably not such a bad thing. Yet, they are not a cinch against Barcelona or even Liverpool or ManU. Their dollars ensure that they will be near the top of the EPL table; however, their dominance over the past two seasons of the top of the table owes itself just as much to issues (transitions, poor decisions, ...) among the other top tier teams such as Arsenal, ManU, and Liverpool (improving but still very short on reliable strikers).