Its sort of like a block. For me, I can't say Ball if it is the first word of sentence or if it is by itself. When I saw Cab, I have no problem. I think this Is because the words flow together. It is not Cuh Ahh Buh. Its Cab. It all flows together and makes the A sort of began the b. I can say any word while talking quietly too. Also, when my throat is relaxed, I don't stutter as much. Sometimes, If I don't move my mouth very much, I don't stutter as much. This is because it tricks myself into thinking it is all 1 word. You can also try to avoid saying R, but you can also do this flow thing I am talking about. Maybe say "The Router" and say it quickly, so it sounds like 1 word.