I think you've gotten spoiled by recent races! That we have had the greatest women's miler ever (Faith) racing at the same time as the most versatile ever (Hassan), overlapping with 2nd fastest Ethiopian all time behind Dibaba (Tsegay) and someone like Muir who not only is fast but historically races a lot, has skewed what Diamond League 1500m usually look like. It has been a golden age.
I remember some grim Diamond Leagues - Kate Grace winning a 4:27 mile, Laura Weightman winning one in 4:06, Arafi in 4:02, or the dark dark days of London 2013 won by Mary Kuria (who?) in 4:08. This field still looks to produce much better results than those meets.
- The women's mile has interesting up and coming stars: Haylom and Chemusto are breaking out.
- Meshesha is only one year removed from a 3:57 and already opened warly May in 4:02. If she makes the team for worlds she could be a medal contender.
Mageean ran 3:56 last year beating Hailu twice and Muir once in the process. She has had her fastest ever opener in both the 800m and 1500m.
Stafford is coming back from injury but is cutting time off every time she races this year so will be interesting if she takes another step forward. Her worst finish when healthy as a pro at worlds/Olympics is 6th.
McGee, Hall, and Hiltz are all world/Olympic finalists all running well.
Andrews might not be a world finalist but is certainly of that calibre and running very close to her PB.
It isn't Florence, that was basically a world final rehearsal race but that isn't normal. This race is maybe slightly below average but it's still a field with decent depth, decent quality, and it will be exciting seeing who emerges from the race victorious.