the problem with that oversimplification is that united hasn't had rooney, ferdinand, vidic or evra poached. even liverpool hasn't had gerrard poached. those players were all retained through their peak years.
if your wages are competitive and you win things every so often, you'll have a good chance at keeping the team together. we kept the invincibles together through their peak years as well, at a time when we had a fraction of the financial power we do now. true, there were no oligarchs in the premiership yet, but we were able to fend off the traditional european powerhouses.
