His contribution to Albion's midfield - sitting in front of the back four - has benefitted the Baggies' defence but also complemented other around him, notably Youssouf Mulumbu, who has flourished.
"He has been top class for us," said Swedish international Olsson told the Birmingham Mail.
"I don't think it is only that, there is so much more.
"His ability on the ball is very good as well.
"With him and Youssouf (Mulumbu) also sitting in front of us it is a big help to the defence.
"He has been brilliant and that is credit to the coaches and scouting staff, finding such a good player and on a free - that is incredible.
"For a player to come from South America and adapt to the game so quickly is remarkable."