"He was one of my best signings," Wenger told Arsenal Player. "He was a guy I liked very much because he was fully committed and made a very difficult decision to join us in his career.
"Therefore I think we always have good relations with Sol here and when he came back I respected, like Thierry Henry, the effort he put in. His winning attitude was still the same when he came back and we have huge respect for him here.
"[We needed someone] who knew the Premier League at the time. We had an exceptional back four before and we got another exceptional one because people forget that Lauren, Kolo, Cole and Campbell were excellent.
"The question was how we could rebuild the back four but I think this one was absolutely exceptional."