I really liked what I saw of Junichi Tazawa in Spring Training (on television). He had an aggressive style, coming after the hitters, with a fastball with good movement and a better breaking ball than Daisuke Matsuzaka. He threw strikes.
Tazawa went to AA Portland, and what has he done lately? Let's focus on the appearances in May.First, I like to look at WHIP (walks and hits per inning pitched) and K/BB ratio, that predicts ERA better than previous ERA itself.
In five May appearances, Tazawa has pitched 28 innings, yielding 21 hits, with 7 walks and 28 strikeouts. He has allowed five earned runs, with the WHIP ratio of 1.00 and the K/BB ratio of four.
No doubt the Sox are working on fastball command and secondary pitches, but it looks like Tazawa has already achieved dominance at AAA. Next stop Pawtucket. Obviously, we don't know Taz' support system (interpreter) et cetera, but the Sox need to assess his abilities against better competition.