Lets see him outside of South Africa, bangs it on the spot at 135 and gets a bit of help from the wickets they play on. Will never rival Steyn as the premier bowler but if he can continue some sort of form I fancy Morkel at 145kmh bouncing them everywhere would be a terrific first change weapon for a captain.
A greater reflection of what he might offer is his form in the shorter formats where the pitches aren't that conducive to his style of bowling hence why he hasn't been as succesful.
As to why they hadn't picked him, like everyone else in test cricket the fascination is with left armers and both Parnell and Tsotsobe have been used before him.
As for Tahir I have doubts, a person who has played for so many first class teams raises serious doubts with me, i think it is pointed out in his profile but I believe it leads itself to an asuumption that he may struggle for consistency over a period of length. BUT his first class record is outstanding and he is a leg spinner...