I tend to agree with toddsyr. I don't know of a cool season grass that needs a 4" cut. Granted, you cut it higher when you first install the sod as that will help root development, but it's been 2 years now and roots should already be established. I've got a customer who needs 'walker' to help her get around and she likes to be out in her yard. Long story short, she MADE me almost scalp her yard (against my wishes and better judgement) .....so I did. Customer is ALWAYS right. Yes? Yes. And it's turned out just fine. (I 'cheat' a little in warm weather) Your bluegrass is a spreading grass (if it's kentucky blue) so you've had 2 years to develop root growth. I don't know what part of the country you're in, but where I'm at, it gets hot, but we're mainly a cool season grass region where bermuda is a PITA. So, what I'd do is cut your grass at you're highest, come back 2 days later and mow a notch or two lower and then mow normally. Does that 'brown/dead' look go away for you now? I bet it does. And, there's been 2 times where I've accidentally 'dropped' my deck to the ground.......both times that grass has come back. That lawn sevice MAY just be doing a CYA! Cool season grass height should be 3.5" in hot, shorter in cooler weather.I'm not trying to be rude, but did you read the original post in this thread?
Lemme guess, if you were to wait a week between mowings......you'd be mowing 7-8" tall grass. Yes? I fired a customer for not letting me mow, for free, 3 days after scheduled mowing and then mow on normal schedule. Reason I wanted to do that? Because you're not supposed to cut more than 1/3 of the blade and I was double and triple cutting when only getting to mow once a week. Hard to do with most customers, but it was more a PITA for me to mow a green 'wheat field' once a week than to mow 'normal' grass twice a week.