<p>Once you've been accepted, how much do the mid-year grades really matter? like is getting 2 or 3 B's a big deal?</p>
<p>There is no hard rule for this. Acceptance letters usually have some statement like, “this assumes that your final grades are consistent with your past record.” You can judge for yourself how consistent it is with your past grades. Small deviations should not be an issue.</p>
<p>Top schools clearly want self-motivated students who love to learn and are disappointed in anything that suggests, “eh… I only strove for A’s to get in to a good school, now I will relax and just get passing grades”. Rescinding offers is not fun for all involved.</p>
<p>You can also read the reports of rescinded offers elsewhere on CC to see the details.</p>