It's 100% team spirit related (I can prove that, as
@Deco has already said, by starting an ML as a team with great TS and discovering a completely different gameplay experience).
I'm convinced the way that team spirit works is heavily linked to the level of the team you're playing, with slightly crazy results.
I played Southampton away on Top Player last night, and it finished 0-0, but I had 14 shots to their 3, and I was disappointed because it was unrealistically easy. So I quit the game and restarted (must be the first time I've ever quit the game without saving because I felt like
it was me cheating).
I played them on Superstar, and their build-up play was - and I don't say this lightly - bullshit. No time to react to anything, no time to plan. It was the extreme opposite.
Let me clarify - I am NOT SAYING tiki-taka isn't realistic, or that I don't want to see it even from Premier League teams, but what Southampton were doing WAS NOT TIKI-TAKA. It was psychic, no-looking, first-time passes strung together 3-4 in a row, the kind of stuff 12-year-old FIFA players do with Accrington Stanley by spamming buttons.
So, the next game (on Superstar), I played United in the league, with no changes, and it was a walkover. For ME (HULL). I ended up winning 3-0 (BUT the goals were two headers and a shot from outside the box, I still couldn't dribble inside their box). Again, the extreme opposite end of the scale.
So, again, I quit the game, replayed it on Top Player, and guess what... I got beat 2-0. Didn't stand a chance.
It's almost as if, with a poor TS (or at least between 50-65), the game "flips" what should happen.
In my experience...
With TS <70, against the average teams, it's not a big challenge on Top Player and unrealistically, frustratingly spammy on Superstar. Against the big teams, it's the exact opposite.
With TS >70, I suspect that "button-spam" doesn't happen so much and the game generally feels wonderful. Though I wonder if it gets too easy (I'll never manage a big team anyway, don't enjoy it)...