wateva, this is the story of my life and I somewhat managed to change it, but it's an every ball effort!
I played College tennis and would literally beat the top player of the team and then lose to number 10 a few days later. It was awfully frustrating for me, but also to every member of the team
I came to realize that I really struggled to beat 'weaker' players because of two things: 1) looking at every ball like an attacking ball and 2) lower intensity/focus/footwork.
1) It's really about point construction and Shazarenka is right. When facing weaker players, I felt like every single ball was a ball I could attack, and I therefore would go for it. Whatever quantity of talent you have, an attack is not safe and will create UEs: if you hit every single ball like an attacking shot, of course your UE count will be high. In my second year, I decided to play tons of matches against 'weaker' players or players ranked lower on the team, and realized that when you are a superior player, you can show it in multiple ways, not just by trying to hit a winner on every ball. Angles are especially important: try to work on getting a really got angled backhand, which usually goes to the weakest side of your opponent and will just open up the court easily for winners but without having to paint the lines. Give yourself more margins when attacking and follow to the net: you'll either force an error, or get an easy ball you can easily finish with a volley/swing volley. You don't have to finish the points with 2 shots, but you don't have to run around and do it in 25 either. Just aim at 5-8, finishing with 'easier' winners.
2) Make sure you hit every ball, and play every point, with the same intensity. The fact that you hit winners out of crazy positions means that you are awfully focused for those shots, get an adrenalin boost, and probably have much better footwork. When a ball looks 'easy', it often leads to bad footwork, laziness. I fight against that every time I play: I would play incredible points when down 15-40 on serve, or in huge important points, but would play quite badly to go down 15-40. Focus on your feet rather than the resulting groundstrokes, you'll realize that moving well makes everything much easier.
In the end, it's tough to realize that in tennis, a screaming running winner is worth the same amount of points than a double fault. But once you get that, you realize that you have so many ways of winning a point that it somehow is reassuring.
Hope this helps! Don't hesitate to pm me if you want specifics, I miss coaching