Ok, cool... you want to dig in, your first message didn't give that indication.
One of the things I do is teach high school kids college level (AP) music theory... if I seem harsh or "snarky", it's because I'm used to dealing with slackers that think information is knowledge.. it's not! My advice on reading manuals and figuring out things for yourself is right on, I know that from years of experience and success with students. I make no apologies for my delivery. It's the only way to really "know" Logic.
You can go on Google and type What Is MIDI right?
Anyway, here's what you can do with MIDI in relation to the Roland.
MIDI is not sound, it's a very small amount of data that "represents" the physical playing of (in this case) your Roland set. Each drum is actually a MIDI note or pitch. What MIDI does is allow you to record (in time) what drum (pitch) you struck, how hard (velocity) you played it, the duration (more important with keyboards...etc) and other data that may affect the performance. Depending if you have quantization enabled.... once a MIDI performance is recorded it can play back your Roland set with the same nuance of the original performance. Plus, now the notes are on a piano roll display and you can move them in time and adjust velocity as well as draw in or step-write things you could not possibly play. And,,,, you can also change drum sounds because MIDI is just a performance playback medium.. it's data your synth understands. Once the performance is the way you want it... you can play back MIDI and record the audio out of the Roland for further sweetening.
So go record a MIDI performance.. if you want it to not sound robotic, turn Auto Quantization off, (it's in the manual)
Logic may call it "real-time" quantization.