Cricket lovely cricket

I have always loved proper test match cricket but never bet on it until the current test. What I have managed starting Wednesday evening is to back the draw at 5/2, NZ at 4/1, and England at 8/1. I have not been glued to the computer, just worked on close of play odds Thursday and Friday. Given reasonably evenly matched teams and the usual ebb and flow of the 5 day game it seems there are real opportunities to assure a profit by a bit of Dutching. Surely this is too easy and I have stumbled on a freak occurrence. Any regular cricket punters out there who can enlighten me, please?