Interestingly though, Lucas said in a recent interview that he found that he couldn't play box-to-box in the league, and thus decided to concentrate on being a defensive / holding midfielder after Benitez tried him there a few times. Some statements he made in the interview are a bit odd though.
http://www.liverpoolfc.com/news/latest-news/lucas-i-had-no-option-but-to-change
Lucas: I had no option but to change
Lucas Leiva has spoken frankly about his struggle to cut it in the Premier League - admitting that he had 'no option' but to change his game in order to become a Liverpool regular.
In a new show that will air on LFC TV at 9pm GMT on Thursday night, the Brazilian talks openly with midfield legend Jan Molby about his difficult start to life in England.
Like Molby, Lucas recovered and went on to become a Kop favourite, but having arrived from Gremio in 2007 as an attacking midfielder, the 26-year-old had to sacrifice his offensive qualities to establish himself in the team.
He told Molby: "I had to change the way I played, used to play. I just thought I had no option.
"The way the Premier League is with the pace of the game and everything, I was not able to do that [be a box to box midfielder].
"I couldn't do it so I just felt, 'Listen, you have to understand that the league is different. If you want to be successful you have to change.'
"A holding position was a position that I felt more comfortable in.
"Rafa just played me there for a few games and then I started to adapt and play some good games.
"I got better as well, I went to the gym, went on the weights."
Lucas's performance in a deeper role became so consistently good that in 2010-11 he won 40 per cent of a fans' poll to be named the club's official Player of the Season.
He admits that one of the turning points in his Anfield career was the departure of Xabi Alonso to Real Madrid in 2009.
"I think my third season," he explained. "It was when Xabi left. It was more pressure but I had the chance to play more games.
"In the first two seasons I was playing but not very often and I used to play maybe 15, 20 games, but coming on as a substitute from the bench is not the same.
"So, the third season when Alonso left I knew the pressure was so high but I had the chance. So I played that season maybe 60 games. Or 55. It was a lot.
"Of course Aquilani came to replace him and they didn't even remember me at that time, but Aquilani was injured so I just played, played and played. I think I did a good season.
"When I finished the season I felt really well and strong and then Rafa left the club, so it was an odd situation for me to think about.
"But maybe the last two seasons it's been a comfortable situation at the club."
The first edition of 'Then and Now' will premiere on LFC TV on Thursday night at 9pm - but LFC TV Online subscribers can enjoy it in full on demand now.