Srna was only a year or two ago being chased by Barcelona, Man City etc. As has already been pointed out, Ivan has the cash, its a free transfer and the wage is small for a player of his caliber.
He was one of the best right backs in the world not long ago with vast experience at the highest level. We need winners and people with that mentality to take us to the next level. I believe that for the younger players especially, his presence will be invaluable.