Rafa Benitez last managed a football team in 2010, his ill-fated tenure at Inter Milan coming to an ignominious end in December of that year, when his performance at the head of a team that Jose Mourinho had won the treble a few months earlier with was deemed unacceptable.
Benitez was not a success at Inter, and his last year at Liverpool didn't reach the standards he had set there, but his record is still very good, and it's surprising that no club has convinced him to join them in the past two years.
Benitez won two La Ligas and a UEFA Cup with Valencia, and reached two Champion's League finals with Liverpool, of course winning one of those with the miracle in Istanbul. he also claimed a FA Cup with Liverpool and took them to second in the league.
He made some very odd signings in his time in England, but he also brought in genuine superstars like Xabi Alonso and Fernando Torres. He also made several signings that Liverpool have only really seen the benefit of since he left the club.
Lucas Leiva, Jonjo Shelvey, Suso and Raheem Sterling have grown in prominence recently, each was signed by Benitez. Suso, who could end up the pick of the bunch, attributes his moves to Liverpool directly to Benitez convincing him it was the right thing to do.
Benitez clearly has a record of winning trophies, and also links with players in Spain that means he can convince the some of the very best and most promising players to join his clubs.
These two attributes make him an attractive proposition to plenty of clubs. He has gained a reputation as a spiky personality, not least from his confrontations with other Premier League managers, but he is also a renowned tactician. Particularly towards the end of his time in England there was a lot of harsh words about his style of management, perhaps it was time for him to move on, but he was clearly still an excellent manager.
AC Milan may have then seen a Benitez failure at first hand during his time at Inter, but he can not be judged by this period alone. Managers have struggled before when trying to replace Jose Mourinho at a club, and many will probably struggle in the future.
Benitez has an excellent knowledge of the game, good links with players, tactical acumen and a record of winning trophies. The Spaniard shouldn't be out of a job for much longer, if AC Milan do end up looking for a new manager soon, they could do a lot worse.