This is the biggest adjustment a lot of people haven't made yet.
With the change to LB speed and overall coverage skills, LBs are subpar in most coverage situations now, either zone or man. With very few exceptions, they'll get absolutely roasted by WRs, and will struggle with top-shelf TEs and receiving backs.
And when I say "very few exceptions", it's actually
very few...the number of competent coverage LBs this year is tiny. A guy who's ok-ish against swing passes to a back won't cut it...I'm talking like prime Kuechley levels of coverage ability to hold up in this year's game.
Like in the real league, you absolutely have to avoid leaving LBs alone on a hook curl or a 3-rec against a slot WR or better TE...it's a huge mismatch, and they'll get destroyed. You absolutely can't just keep running base against 11 personnel groups and count on a user LB to hold up in coverage anymore...even 12 personnel is iffy (I usually go big nickel againt 12).
Swap a S into at least 1 SUBLB slot (preferably a good Run Support guy, to help out against runs out of 11 personnel looks, which the CPU is also doing more of). Run at least nickel personnel against 3 WR looks...dime on obvious passing down-and-distance and 4 WR or empty sets. Play smart. Call the right zones against the right sets (trips, bunch, etc), and learn what Sky, Buzz, Match, Quarters, Palms, Hole, Robber, and such mean if you don't already...they matter this year.
I strongly suspect a large percentage of the issues people are reporting with both man and zone coverage, especially with underneath passing, are the result of just not having adjusted to this change yet, and they still have LBs out on a slot WR out of a base 4-3 or 3-4 set.