Hello I'm a Diamond 2 player,

I mostly play sentinel (Cypher) but lately I can't seem to get atleast 15 kills a match. I always follow my daily routine warm up but I just cant seem to have a good game. Whenever I'm winning a match, I'm the lowest frag but when we're losing, I'm the highest lol. Anybody here can give me some advice, I just need to atleast drop 15 kills a match as a sentinel or atleast have a feel in my game that it's consistent.