You can strengthen squad by buying strong players via offers (usually from events etc). You can also use a trainer to increase star level of existing players. Plus (as you state, by doing extra team training).
I do not mind not being top, I haven't won the league for a while. But I do mind being indirectly asked to buy tokens and then after I don't, failing to win 8 out of 9 matches against a lot weaker opposition in league & cups.