The signing of Tatsuya Imai is important for several reasons. First and foremost, the Astros have added an incredible piece to their rotation that's now looking like one of the best in the division. Scouting reports from early in the offseason suggest that with MLB pitching development, he could kick into an even higher gear, but as is, he's poised to be a solid middle-of-the-rotation arm.
His impact may be short-lived, given the opt-outs after each of the first two years, but at the very least, Houston will get some starting pitching depth for the time being.