The Bianconeri were forced to play without several starters in the match, but the Italian stepped up and scored a brace en route to a 3-1 victory.
Pirlo pointed out that Chiesa was brought in to make Juventus unpredictable in the final third, as his play at the San Siro posed problems for the in-form Theo Hernandez.
“The idea was to keep him [Theo Hernandez] under pressure and not allow him to push forward as he usually does, especially when he had to deal with someone [Chiesa] that is also good in one-on-one situations,” he told Sky Sport Italia.
“We signed him so that he could take on men in the final third. While his position may change, his role does not.”
Milan levelled the match thanks to a Davide Calabria strike before half-time, but Juventus’ depth made the difference after the restart.
“It was important for us to win as we didn’t care about the results of the teams ahead of us in the standings,” he added. “We are focused on our own progress. We’ll see where we are in a few months.
“The important thing is that the team showed they want to be in control, especially against the Serie A leaders on their home ground.”
Juve felt Milan’s goal should have been called back due to a foul by Hakan Calhanoglu on Adrien Rabiot, something Pirlo reiterated after the match.
“It was a foul and the referee should have blown his whistle,” he stated. “Danilo should have been more aggressive after the decision was made, but the whole team was out of position. Regardless, it started from a foul.”