Sakib actually had bowled few really good spells, you (not only you, most here) hardly watched BD cricket before 2015 I believe, hence it's understandable. First, a spinners bowling can never be matched with a pacer, because of the different operational mood - a spinner works on the fundamental of building pressure & slow burn, while pacers often try to force the issue in short spells which helps him to preserve energy. In that regard, Sakib actually did wonders for a team that always licked 4+ runs from other end & often bowling with 300/400 runs on board already. I think, he has about 9 5fors against top 8 sides & most of them in 1st innings, which itself is tougher for spinners.
Personally, I don't rate AF that much, who was over blown for that Ashes win in 20 years.