Malinga alone wouldn't have made a credible Test attack. They really need two of him to have anything above average.
It's a shame he didn't have the body/action to play more, but SL aren't missing anything, because they basically never had him!
Its a bit like Flintoff's retirement in a sense. Towards the end of his career he was more of a distraction as everyone was unsettled with him constantly looming over the team with his various comebacks. Possibly a good thing.