Interesting to me that the massive amounts of money available to the bottom 14 EPL teams has neither improved the style of play nor breached the gap between them and the top 6. Teams in that group of 14 generally place high in lists of wealthiest clubs, above everyone but the top 6 EPL and an additional 5-10 in the rest of the world. Yet they continue to struggle to compete.
AIAFCT, 2 factors came into play: the increase in available money meant that (1) clubs selling into the EPL raised their price demands, and (2) what additional funds remaining was captured by higher player salaries. The clubs could neither make a profit nor afford to acquire higher quality layers. The sea level rose but they are all just still treading water.
And I think this is why MLS keeps inventing new special limited rules to let clubs spend more money. Garber et al have figured out that if you just spend more money on players, then a lot of it just ends up in the pockets of players you already have, or who have no choice but to join MLS, and the league does not improve. You can criticize that on grounds of fairness, but from the standpoint of efficient spending and the goal of improving the league, these crazy rules make sense.