I would not count much into that. Nazmul only played one ODI in Srilanka at RPS. He was able to grab only Jaya's wicket with an outrageous economy of 7.62, actually he was the maximum run giver that day. His successes against Srilanka mostly happened in home. In 3 matches he has 7 wickets with a BBI of 3/30. But in terms of economy Mash and Rasel are way ahead.
Whereas Rubel played 4 matches against Srilanka at home with a BBI of 33/4, he never played away match with Srilanka. Considering his current lack of form he might not be a good choice right now. If we go by the golden rule of choosing players leading the domestic Tapash becomes an automatic choice I guess.
For test whereas Shahadat Rajib, the only BD bowler who has his name curved on Lords List is leading miles ahead. He has a better average than Mash and has a 5-fer against them and grabbed 23 wickets in 9 matches he played.
Human mind has all the power, when your mind is grind grit wins the battle. Go Bangladesh. Be the world number one in Test Ranking.