How can a win result in no elo gain?

I know his elo is much lower than mine but come on, I still had to play for like 3 days and I do risk losing a ton of elo if a I get a bulshit spawn. I have been getting 1 elo per victory from anyone in the range of 950-1150 as matchmaking keeps putting me against low rated players, and I dont mind, but to not make any progress at all is a little bit frustrating. Thoughts?

I know his elo is much lower than mine but come on, I still had to play for like 3 days and I do risk losing a ton of elo if a I get a bulshit spawn. I have been getting 1 elo per victory from anyone in the range of 950-1150 as matchmaking keeps putting me against low rated players, and I dont mind, but to not make any progress at all is a little bit frustrating. Thoughts?