Kuroda is a good #4-#5 pitcher. He's not someone I would ever want to count on in a top 3 of the rotation, or in a post season match up.
That said, if Hughes steps up, he could take the #3 spot.
To be honest, I was never all that impressed with Pineda. He's a big guy, got a big arm, but he gets torched in small parks.
Not trying to be biased, but I don't think the Yankees rotation got all that much better to be honest. Look at last year.
You had Colon who posted a 111 ERA+ that you are replacing with Pineda, who posted a 103 ERA+.
Long term, definitely a big step in the right direction. But it's kind of like when the Sox replaced Beltre and Vic with Gonzo and Crawford. In 2011, the production was projected to be similar. But going forward, you were getting much more production with Gonzo and Crawford than you were with Vic and Beltre.
The big step is obviously Kuroda (121 ERA+) over Burnett (86 ERA+). But - a lot of that will be offset if Kuroda returns to his career norm of around a 111 ERA+, and if Garcia returns to his career norm of around a 109 ERA+ (he had a 122 ERA+ in 2011).
Summary -
Pineda + Kuroda (2011 numbers) = 224 ERA+
Burnett + Colon (2011 numbers) = 197 ERA+
If Kuroda and/or Garcia return to career numbers, that would offset that quite a bit more (anywhere from 201-214 for Pineda + Kuroda).
Looking at the numbers a little closer, I'm not all that impressed. I don't think they made as big of an addition as it's being made out to be.