A fast trainer:
1. Young player 18-21(22) yo.
2. Very expensive (very very expensive)
3. In the old version: train him 3 bars practice match and he will improve by +80
4. In the new version: (not very sure) train him 6 drills fast counter attacks or press the play and he will improve about 4-5% attributes or 1-2 in special ability/position every training.