Looking at their boxing history it seems like Ruiz is the more experienced player here since he played 10 more matches than Joshua. But Joshua is undefeated in his career winning by knockout in 21 out of 22 matches played. Alslthis will be the first match he plays in America, a good reason to gather himself and put on a good show. I agree with your pick and for higher odds I will also try Joshua to win in first 3 rounds.