Massimo Ambrosini struck for Milan before Cristiano Lucarelli's second-half equaliser.
Leonardo said: "This was not an easy week, but they were three different situations. Winning with Inter could've changed the course of the campaign.
"Then we went out of the Coppa Italia, while today all we were missing was that finishing touch.
"We needed a good performance. It wasn't great against Livorno, but nor was it awful. We didn't take the chances we created against a very defensive side."