You may be able to get a better read if you pull up an opposing team's stats, then click on the starter and in the top right portion of the (player profile) popup, it'll list his "position" (S1, S2 longA etc) as listed in the opposing owner's manager's setting.
Then you can hit game log to see when he pitched last and figure out the rotation from there....
Now, the owner can snooker you if they are doing the same type of scouting as you.
I usually only use it when playing terrible teams, so I can adjust my rotation and save my ace.