Much was expected this of the San Siro outfit under the guidance of Filippo Inzagh this term, but the club have failed to deliver and face an uphill task to achieve qualification for Europe.
Poli has made 28 league appearances for Inzaghi and admits more could have been done throughout the squad to improve on their current eighth-placed position.
"It's not easy to explain what's happening," he told the Gazzetta dello Sport. "The injuries played a part in it, but in general it's been a combination of factors that kept us from developing a continuity.
"Football is cyclical and it takes time to get a reconstruction going. That said, we wasted a great chance to shorten Milan's regeneration phase.
"We aren't happy. There's little to be said and a lot to be done.
"Judging by the season, all of us could have done more, myself included. But now we're focused on rebuilding towards something important."
And the 25-year-old says Milan should focus on creating a side around their homegrown players if they want to be challenging Juventus for the Scudetto next season.
He added: "I think that in our squad there's a good core of Italian players that can provide the mainspring to start again. We can all be leaders together.
"When Milan dominated in Europe, there was a core of Italian players. Now in Milanello there's a nice group of experienced lads who feel the Rossoneri colours very strongly. It's a good project."
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