As much as we all love Sergio, there's no room for his current lack of sharpness and dare I say it lack of interest being shown. To be fair to him on Saturday he was feeding on scraps, especially that 2nd half, but his body language isn't good at present.
He certainly hasn't linked with De Bruyne yet, and I reckon he's missing Silva big time. Silva is probably the key for him to get going again.