Anyone had a lot of recent rain and have noticed Buffalo lawns suffering?

2 residents at work have buffalo lawns that aren't looking the best.
Asked me to spray them for army worm, but I knew it wasn't the problem.
One lawn is fine out the front, got slight yellow patching out the back. He
recently fertilised the back, so my guess is fertliliser burn. A pH test
showed levels around 6.5, so it's ok.
Haven't checked the other lawn, but overall it looks like it's dying from a
distance. I noticed some edges where it wasn't mowed were green, so it might
be as simple as scalping, but I doubt it.
We had a hell of a lot of rain here 2 weeks ago, highest in the state I
beleive.
Wondering if that had anything to do with it?

Any suggestions?
Our boss suggested the bad lawn may need a slight fertilising of something
that's high in Potassium and Phosphorous.

Thanks for any help.
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