How exactly is this bad? The guy has close to 30 minutes for 10% of battery life, so proportionally close to 5 hours total screen on time for a full charge and this is supposed to be abnormal? Screen on time is purely on what you should base yourself first because you have no idea on what the phone reports as "Android system". As far as I know, if you had 5 minutes of screen on time instead of 30, that would be a problem worth investigating....but 30 minutes for 10%? You should not try to find issue where there are none.
Let me show you why you can't rely on phone stats. Here is my screenshot for today. Just from looking at it, you can already see i have some kind of huge wakelock problem, severe battery drain, especially if you consider I only have about 1h15 minutes of screen on time. Anybody looking at this could see that there is a problem with my phone. The fact is, there isn't. I had a 4h16 hour conversation today, but, my phone only reports voice calls taking up 12% of my battery life. Thats because other features are not included in the voice calls tab, like how the sensors have to always check if i'm close or not to the screen to turn it on or off, or the fact that it has to manage my wifi connection while using my mobile connection that is about 1 bar in my room. There are too many unknown factors to solely rely on what you see here, or on OPs screenshot. If you have 30 mins of screen time, and have 10% battery drain, thats fantastic. Don't forget, only 1 gen ago, having 3 hours of screen time with a full charge was awesome.