People are making too much of one bad performance by Abbas. He was just coming off an injury and Sarfraz, Azhar + dodgy umpiring certainly didn't make it any easier costing him two easy wickets he should have had. You're saying Abbas doesn't have a good bumper what about the delivery on which he dismissed Theunis de Bruyn? It was a 128 kph bumper but perfectly directed. Obviously comparing him to Asif is unfair because Asif is a very high ceiling but Abbas is still quality. And even when someone like Finch tried to bat outside the crease against him Abbas knew how to get him out.
Our batsmen didn't give Abbas and Amir a chance to bowl on a 4th day wicket which had gotten legit dangerous by the morning of the 4th day and would have been a real nightmare for South African batsmen if they were chasing anything over 200.