Pre-season Steamer had him at 3.2 over a full 162 games, so I'm not sure how you're getting those numbers. For what it's worth, Navarro was around 2.9 over 162.
Beyond the numbers, I like Kratz but I'm not sure how much I'm buying into his bat. He's not a bad hitter at all, but I prefer Navarro's approach and ability to make contact... maybe the JPA strikeouts are biasing my opinion.