Not baseball, but the 4-3-1-2 or 4-1-3-2(Sounders sometimes in this variant), and how it developed and is used in Europe.
What is notable is that while Sounders FC use a formation that could be described this way, they actually abandoned the #10 concept for which Ljungberg was initially slotted. He is more often on a wing or in a second striker role than he is with the ball at his feet about 30 yards from the opposition's goal looking for the forwards.
Also, notable is that though Sounders can be described as a 4-1-3-2 (Alonso at holding), their wing play is actually quite solid, and since Leo came to the club, balanced.
I have described it as Sigi's Arrow, others a Pineapple. The notable difference is that there is no Central Attacking Midfielder in Sounders' system, and that the defensive triangle is anchored. That would be the two CenterBacks and the Defensive Mid. While yes, Alonso comes forward at times, it is then that Evans/Vagenes will drop back into the triangle.
This does lead the Rave Green susceptible to opponent's wing play on a punt, but with several Sounders in the center third they usually own that sector. Also, the wingback that doesn't go forward can cheat centrally to allow the faster CB to move towards the opposite wing.
Sounders tactics aren't likely to work as well in a higher level league. They count on a certain lack of balance in the opposition, poor diagonal passing abilities and a keeper well beyond the league's average skill. BUT in MLS, they are likely to get better when healthy as they learn the system, and understand their roles better, because it is a semi-fluid strategy that bargains on some of the nature of total football and some of the defensive strengths of the diamond 4-4-2.