Hello

I looked at your lawn problems and pictures. I agree with what Ed advised you earlier.
The only observation I would add is your lawn appears to be sloping downward in the problem area. It is very difficult to get enough water to soak in to an area that has a slope. You may want to run an irrigation audit and see if that part of your lawn is truly getting watered sufficiently. Slopes need light frequent watering, and may need a fine spray applied as opposed to larger droplets from sprinklers. After you water, dig down and see how far the water is penetrating on your slope. Below is a reference that describes how to run an irrigation audit. 

And, repeating what Ed advised earlier:

Crabgrass is an annual and dies every year. It comes back in sprink, about the time the foray5ia blooms. If we have extended ,wet periods later in spring, crabgrass continues to sprout beyond the 6-8 weeks a pre-emergent protects the lawn. Thus, a second pre-emergent after about 8 weeks might be necessary.However, most pre-emergent herbicides prevent the growth of grass seed, too. So, if crabgrass becomes a Problem use a post emergent labeled for crabgrass on it- mesotrione, quinclorac, Topramezone or Dithiopyr( info below)

It is nearly impossible to diagnose Specific fungi from photos. You may take a sod sample and submit it to the MSU Diagnostic Lab. The sample form, fee schedule and instructions are on their website at: https://www.canr.msu.edu/pestid/ Once you know which specific fungi you hnave, we cn advise a treatment. In general, you should always water early in the day so that grass leaves dry out before sunset. Grass that stands for long periods of time wet are much more susceptible to fungal infections.

Unless we have a very warm extended fall, it is getting too late to oversee for fall. However, there is a process called dormant seeding that may be successful for you. With all seeding it is important to get good soil to seed contact, ( below any weeds, crabgrass or thatch)and once seeds sprout, whether they be in fall or spring, to keep the soil moist and the young seedlings watered. Kentucky bluegrass takes 21 days to germinate in warm temperatures, longer when temperatures are cold( below 65 degrees). If you have not had a soil test in the last three years or more, it would be a good idea to test your soil and follow the recommend for fertilizing. This helps your grass become thicker, more vigorous and outcompete weed seeds like crab grass.

Check your lawn care practices against the known and proven best practices for a thick and healthy lawn. Here is a summary https://www.canr.msu.edu/resources/go_green_lawncare_tip_sheet

References-

Irrigation audit

https://content.ces.ncsu.edu/landscape-irrigation-auditing-made-simple

Fungal disease in lawns
https://extension.psu.edu/turfgrass-diseases-brown-patch-causal-fungus-rhizoctonia-solani

https://www.canr.msu.edu/turf/diseases

MSU soil testing: https://homesoiltest.msu.edu/

Dormant seeding and spring seeding
https://www.canr.msu.edu/news/late_season_lawn_seeding

https://www.canr.msu.edu/news/tips_for_reseeding_lawns_in_the_spring

Crabgrass prevention-
https://extension.umn.edu/weeds/crabgrass