As a hypothesis, I'll suggest the problem is the IXB-DEL segment as Delta doesn't file a fare IXB-MSP, and 9W's fare(s) has specific routing requirements above simple MPM, at least for the Y2owuc I checked.
Thus it may be pricing as 80K MSP-DEL-MSP, then adding the IXB-DEL segment. That addition is 17,500 + 17,500 because DL redemptions default to r/t pricing. 80K + 17.5K + 17.5K = 115K