Yes, it's your play style. It (like most pitches) is a dynamic grade. It dropped to D+ because your CBs weren't getting INTs (if it was a coverage guy) while other teams' CBs were. It went up to C+ because in the previous week your CBs got some INTs.
It's really basic. If your team does the things well that the recruit also wants to do well (HBs that want your HBs to get lots of yards, WRs that want your WRs to get lots of yards, your TEs that want you to throw for a lot of yards to your TEs, DEs that want your DEs to get a lot of sacks, LBs that want your LBs to get a lot of tackles, etc, etc) then you'll have a good grade. If your team isn't good at doing what they want to do well (that HB wants lots of rushing yards, but you don't give it to your HBs often, that TE that wants to get lots of yards, but your team doesn't throw to the TE often, that DE that wants to get lots of sacks, but your team doesn't put the DEs into position to get lots of sacks, etc, etc) then you'll have a bad grade for that pitch.