It's difficult to really answer your question because, as other have pointed out, all of these players look worse from being surrounded by players that not only are average to below average, but don't have the luxury of being on a team that has been together for a couple seasons and know each other and the system. I believe many people greatly discount, or even forget about completely, that second factor. Fortunately, that will improve as the season goes along, but the talent won't, except for the raw guys like Shelton.
We have a team full of players who, if on a better team, would perform much better as a result. You can get away with having 1 or 2 of those players on the field, but when you have 5-9 of them on the field at once, you get what we are seeing. The only way to truly fix this problem is to keep building this team over the next couple years. Unfortunately this is not Europe where you can pretty much rebuild your roster with elite players during the offseason. MLS' roster and player acquisition constraints makes that impossible. If you look at other successful teams in this league, you will notice that the team was put together over a long period. You will see a player who was drafted 7 years and developed into a star, another 5 years ago, another 4 and another 2 years ago. Then you may see a homegrown player who developed into something. You will see other players who were acquired in various ways over the course of several years and then it will be topped off with a very well picked DP or two. You don't see any great MLS sides these days that have been overhauled completely, let alone built from nothing over the course of an offseason. It will take so many years for us to be able to compete on an equal playing ground with the rest of the league. For the time being, we need to master the use of the DP rule and catch a few breaks along the way.
One of the biggest things that has frustrated me has been our passing and off-the-ball runs. Too often we see two or three players that are on a completely different page. The result is passes to nobody or an opponent, or somebody not making a run that a player expected, or a player making a run and not getting the pass from a teammate. It often makes the players look incompetent, but much of it is the result of a lack of familiarity. And our backline, damn, it's been rough. It's mostly just momentary breakdowns where somebody magically becomes wide open with the ball in front of Saunders. Sure, we don't have great defenders, but again they are not familiar with each other and they have to pay for that. This part will get better, and hopefully very quickly. This is the problem that makes it difficult to really say who is of MLS quality, because the situation really does make everybody look worse.
Take any of one our regular starters out of our lineup and put them into a top teams lineup, they will all rate much higher.