First,tankers are lazy (not all of them lol) now they don't have to think how to train their players, they will train all their players at once,this is a good "deal" for them.
Before the new training system,you could beat a tanking team,let's say 150%(him) easily with a 120% well trained team,now,we will all have the same skills (but the tanker will beat you with his quality)
Tankers don't play only league,they play cup and champions league (i've seen many tankers with a double,cup and champions league)