I can only compare with Union Berlin, the only other team I follow closely and know the ins and outs of the squad.
23 players who are not goalkeepers or under-21. Two of those 23 are sitting out their contracts and haven't played a minute this season or the second half of last season. Let's say 21 senior outfield pros, then.
In their rise to second in the Bundesliga and long time earlier at the top of the table above Bayern, Dortmund and anyone else I can say the following:
A system (5-3-2 with one striker and one man in the hole) that is played week in, week out.
Tailored back-up in every (and I mean every) position...five CBs with different specialities, two RB, two LB (one of whom can play both wings equally as well). Two midfield stoppers, at least two box-to-box midfielders, at least three attacking midfielders/forwards capable of playing in the hole or out wide. Two pure attacking wingers with lightning pace. Two out and out strikers (both physical, one more of a ball player).
It really is fantastic to see week in week out. When a sub comes on and you know he'll do the things well, or you can rotate as many as 4 or 5 players out and feasibly not be weakened to any great extent.
I mean you look at our squad and are there actually any players (proper first team senior pros who are not currently injured or mysteriously unavailable) not in the first 11 or on the bench? Smyth maybe?
OUFC needs more than "Sam Long can play CB, LB and RB" to get anywhere in this league.