Some insight on why stopwatch might be broken.
As you all know, the start of Season 8 is being called the League of Stopwatch. I didn't believe it at first. I thought stopwatch is a good item and all, but then I headed into ranked when the season started. If you look at my op.gg or whatever, I'm a Zed main. He is an assassin. The stopwatch is a good item to neglect some burst from assassins early in the game. I got to promos and lost it a couple of times, most of which due to my inability to snowball early on due to stopwatch. At this point, I've learned to play around it. The thing is, AD mid laners have heavily been impacted by the item. How do I know this? If you go to op.gg and check the Champion Win Rates for the mid lane, the top 21 champions are all AP champions. If you look at the percentages, the top 21 champions ARE ALSO the only ones with a 50% or higher winrate. What I think is that the availability of stopwatch has made mages more powerful and assassins less. That's just the way I've seen it. I know that the mid lane isn't the only one where people utilize stopwatch, but it's the place that has impacted me as a Zed main.
How the tables have turned