The ground instructors were pretty good. We had several during initial training. Everyone wants to see you succeed and if you're having difficulty...ASK FOR HELP! You'll hear this suggestion over and over (and it's a good one)...form your study groups early and study often. If you're new to 121 ops, there won't be much time for you to do anything but study.
The first week (Indoc) is fairly heavy on 3585, duty times, and Mesaba policy/regs. Your 2nd and 3rd weeks will depend on which aircraft you're assigned to. The SAAB folks got 2 days less of General Subjects than the -200 folks. General Subjects is easier because you now know what to expect on tests, but it's more of it. If there are any Captains upgrading, they'll usually join your respective group during this time. General Subjects involves more 3585, duty times, more Regs and the introduction to TLRs. Eventually, you get Systems about 2 1/2 weeks into your ground instruction. The SAAB folks ended that with a written test...whereas the -200 folks took CBT training with no written at all. The tests were given at the completion of each online training module on a "take it until you passed" basis. Systems in the -200 (for me) was easy, but you've got to get your nose in the manuals as Mesaba provides them. Don't skip around...you'll cover nearly every nook/cranny in most of the manuals they provide you. Most of the instructors are good about making sure you know what will be tested (foot stomps), but there are always some surprises along the way. Mesaba instructors provide you with a red binder which contains all the PowerPoint slides they cover in class. You should use those as a reference and note taking...not as a be-all/end-all guide to what will be on the tests. There were many people that downloaded the question banks off MyMesaba.com...don't trust that (alone)...the questions are old. Instead, make sure you jot down any FOM/POM references mentioned in class and read over them later that night. Doing that will help you nail some of the trickier test questions that are not covered in class. Not everything is covered in class.
SIM training is another ball of wax. In the -200, my group worked their tails off prior to coming. We knew our flows and callouts very well prior to actually getting into the FTD and that helped IMMENSELY. You DO NOT want to get to SIM and be lost on flow/callouts or you will likely struggle.
For any -200 guys out there, feel free to PM me for a really awesome ORAL guide. One of my FO colleagues copied the entire thing from the end of the Bombardier CBT Systems training and it was a HUGE help when it came to preparing for the ORAL.
Good luck.