With this first win, at least AC Milan can have better confidence, giving them a chance to top the standings. Lecce is basically not a worthy opponent for AC Milan since they are a mediocre club. The strength of the two teams is certainly not balanced, so I don't think AC Milan strength this season has been fully tested. I think AC Milan true strength can only be seen when they face fellow elite Serie A teams.
However, considering AC Milan is only focused on domestic competition, Allegri job should be a bit easier to get his team back on track. Last season, AC Milan finished eighth, Allegri should be able to guide AC Milan to a top four finish and secure a Champions League spot when the season ends.
Lecce is not one of the strongest teams in Serie A, and AC Milan's victory in that match doesn't reflect the team's strength. The real test will come when AC Milan faces a much more evenly matched team. Lecce a less strong team, can pose a real challenge for AC Milan, as I saw them struggle to break down Folcone's goal in the first half, despite his excellent performance.
Not participating in various competitions should have made it easier for Allegri to fight for a chance to finish higher this season, but judging by the quality of their performance in the previous two matches, it seems they are struggling to consistently achieve wins, and this is something the coach needs to improve.