If the season where to end now, Sterling would be a very serious contender for POTY. In terms of direct contribution to goals we have scored he come first. In fact in terms of productivity he is number one in the league.
Personally for POTY I would go for Silva because he has been super consistent and has been scoring goals of late even from midfield. Not to mention his influence in the middle of the park where he has no rival.
See the stats below:
Top City goalscorers
Aguero 8
Sterling 7
Sane 5
Silva 5
Mahrez 4
Bernado 3
Top City Assisters
Sterling 6
Mendy 5
Aguero 4
Sane 4
Bernado 3
Silva 2
Fernandinho 2
Gundogan 2
Number of points for direct involvement in a goal i.e. goal plus assist score
Sterling 13
Aguero 12
Sane 9
Silva 7
Bernado 6
See how his counterparts from other teams are faring:
Hazard 7+4=11
Salah 7+3=10
Kane 7+1=8
Aubaumeyang 7+1=8
Sigurdsson 6+2=8
Mane 6+1=7
Martial 6+0=6