I have a couple of ideas that would stop tanking
1. All skill points must be allocated before the next match, or they are lost.
2. In real life, after a training session, the manager doesn't decide which skills a player gets better at, the player just gets better, so maybe the skill points are automatically allocated after every match/training session. To give more control perhaps the training sessions should be split into three groups: defence, attack and physical/mental.
The only problem with these is that it would give the token buyers an advantage, but hey Chelsea? Man City? The premier league's equivalent of token buyers