Zia, Milon and Sabbir should be in the same bracket. Difference is Sabbir has the potential to play in ODIs and can play a long innings, changing gears when he needs to. He can also play in Tests in the future too. Zia and Milon can't. It may be worth investing that #7 T20 spot to Sabbir so he can get International exposure.
When asked how he felt making the national team . “Dreams vary from person to person. I may have bigger dreams, maybe that's why I am not over-excited.” - Mominul Haque