Tweener is being used to refer two things as far as I'm concerned.
In both cases, it means exactly "in-between-er"
In terms of rev rate:
Stroker - Tweener - Power Player (can be power stroker or cranker)
In terms of style:
Stroker - Tweener - Cranker
Not as much wrist and elbow manipulation as crankers but more than strokers (or can do both sometimes which Randy Petersen pronounced "Croker" when describing Chris Barnes
It was the first time I've heard it)
