The problem with being a side outside of the top four is that you are susceptible to becoming a selling club. Teams don't establish themselves as top four sides in one season unless they are backed by Abramovich. So in those 3 or 4 seasons it takes to make that big push for the top four, similar to what Everton have done, the best players soon realise that they are better than the standard of Football to which they are playing alongside.
In the next season or two. Evertons best players that are capable of playing at top four sides. Players like Lescott and Arteta, they will think "sod this" i've got Liverpool, Chelsea, United and Arsenal all offering me double my money on wages, and i'll be playing with much better players, at bigger clubs where i'll be travelling all over Europe to places like the Nou Camp and the San Siro every season, and fighting for the big honours at the top of the league and i'll get more of a look in with the national team, oooo i'll have a bit of that !".
When Everton managed to break into the top four, that was their big chance, they needed to invest and invest considerably, and had they done that, they may still be there now, or they would be a damn sight nearer thats for sure. But they didn't and they are now in the Uefa Cup once more, building back up to that second go. Sadly, it is all about money, and when you get your chance as a team you have to take it, Everton didn't, Liverpool spent more and the gap between the top four and the rest widened.
The gap between the top four and the rest now is almost as big as the gap between the Championship standard and the Premiership standard, don't let individual results fool you, the league table doesn't lie. And the fact is Liverpool have grown ever closer to the top in the past 3 seasons. The introduction of Torres and the reinvigorated Gerrard will only increase their chances next year, throw Barry and a couple of other top notch signings into the mix and they are as good on paper as any of the other top four teams.
I hate the monopoly of the big four, and my teams part of it for christ sake. It makes the league so predictable and sadly it is going to take something rather dramatic for any one team to bridge that gap. It would take Liverpool or Arsenal to sell a big game player like a Torres/Gerrard or a Fabregas/Hleb and a couple of dodgy replacements, and a Villa, Pompey, Everton or Blackburn to spend big and get a whole lot of luck to even come close to bridging it.
As for Barry's versatility and its use at Liverpool i don't think that will be a problem. They are losing Lucas and Mascherano to the Olympics for the first month of the season and Alonso is being sold to Juventus. So he will be vital in central midfield. His versatility will only come into use if there are injuries on the left side, and with the depth that Liverpool have over there i don't think it will be a problem.