The Bianconeri were twice leading on Saturday night, but pegged back to a 2-2 result by Genoa in Turin.
“Now the dropped points are starting to weigh on us,” said the midfielder.
“We cannot take the lead and then close down hoping the game will come to an end the way we did tonight.
“We had scoring opportunities, such as Giorgio Chiellini’s two headers and Mirko Vucinic in good positions. When these situations occur, we must make the most of them.
“We’ve got to be more clinical and finish off matches. It’s also crucial we maintain the tempo for 90 minutes. We’re still in time to improve, especially as the progress from last season has been notable.”