Mike Trout has a .345 BABIP. You really think the 8 point difference is going to be a difference maker? Mike Trout is overrated because he's coming off a season in which he had a .384 BABIP and he plays great defense. I would have sold high on him and tried to squeeze more than just one player out of him, but if someone offered Segura for him and I didn't have a good shortstop, I would accept the trade.
I don't think you read what I said, I said compared to other players at their position, Segura is likely to perform just as well. Outfielders are a dime a dozen. Shortstops are much harder to come by. Among shortstops this year Segura's in the top 5 of OBP, R, RBI and SB (TB isn't listed in fangraphs but I imagine same goes for that stat). Among OF, Trout is 7th and 15th in some of those categories. You might get similar value from Shin-Soo Choo in centerfield.