"We'd done our homework on him and studied him on our DVD system, not just looking at his good bits and highlights but the good, the bad and the ugly," said boss Tony Mowbray.
"He came in and trained for two or three days and scored a good few goals, then he went to Blackburn with us and scored two goals in seven minutes and could have had another two or three.
"There's enough there for us to offer him something short-term to see if he can get up to speed with the English game.
"He's played in France, Spain and Greece but the English Championship is a lot different to those leagues. We've seen enough talent and goals to see that potentially he could add something.
"I wouldn't want people to think we've signed Lionel Messi. He's an out of work footballer and there's nothing involved finance-wise other than salary.
"But he's got a few assets. He's played for his country, he's played in La Liga, he played for Paris St Germain at the age of 17. In training he seems to know where the goal is with both feet.
"It's an opportunity for him and an opportunity for us to create competition in an area of the pitch we've been looking to add to.
"For whatever reasons, he ended up going to the Emirates for a year and to Greece.
"We've seen enough to give him an opportunity. Whether he can force his way into the team, we don't know."