Here is my understanding of rotational/linear... FeetFirst....pick one best suited for the individual hitter.
Not seeing both in either of these...perfect examples. (JMHO) Thinking I'm seeing the problem.... besides it taking me 2 days to just simply post a comparison side by side of the two. The basic terms rotational/linear are conflicted... Sorry gentleman, but that's how I learned to identify the mechanics. I'm not disagreeing that they can be combined, just not from scratch... guessing???
I see three differences here that I think make the swings look different:
1) Stride/no stride. Greenmonsters mentioned this already.
2) Stance. Longoria starts a lot more upright. I don't know what it means though.
3) The most important: Pitch location! Longoria appears to be swinging at a pitch letter high and a bit in. Kemp is going after a thigh-high pitch that I think is down the middle or close to it. Maybe a bit in? IOW, I think Longoria is adjusting his swing to hit a high ball.
I'm obviously not claiming to be an expert on any of this, just saying what I observe. And I could be wrong. I don't know enough about rotational/linear to recognize the differences quite yet, but I'm not sure we're comparing the same thing here.