I could argue that they are if Jacksonville doesnt make it. Cle isnt better than Buf, Mia, or KC. So the argument comes down to them vs Houston. Flacco is about to be exposed in a big way but I know people dont want to see that or believe it.
I'd argue the biggest threats in the AFC to Baltimore are Buffalo and Cleveland... but that's different than my objecting to Mackus saying Cleveland is clearly one one of the two worst. I can see them being lumped in the same tier, and I can even see liking some of the others better... but I can't see saying Cleveland is 'clearly' below.
Miami is a shell of themselves with their defensive (and offensive injuries). Plus we will see what Tua and a timing offense looks like in January if they have to go on the road and play in the wind (their offense has been drastically worse on the road all year, just with the opposing crowd noise impacting their pre snap reads and movement). They also haven't shown they can beat good teams.
KC has the pedigree, and I was hanging on all year to that giving them respect... but their defense has come apart lately, they don't run the ball, the oline isn't good, and the WR's aren't going to all of a sudden start getting open and learn how to catch. You start with Mahomes, and Reid, and their accomplishments... and it's not unreasonable to believe they could beat anyone in a given week, but I don't believe they are as good overall as Cleveland right now.
Buffalo has been winning games, but they actually haven't played all that great the last few weeks. I think they are a better team if they feed Cook. I expect they beat Miami tonight.
I don't think Cleveland is anything special. 4th QB of the year, injured backs, etc. But the defense is above average (better at home, but still good overall). That travels. As mentioned by you and others, they've got the familiarity of playing the Ravens. No surprises for either. Flacco is turning the ball over a lot, but he's doing some of that by design. He's attacking down field, not just checking down. Their offense has gone from like 26th overall to something like 8th overall since he came on-board. Flacco isn't going to be wetting himself in any playoff atmosphere. And they're also playing with house money. They've got the disrespect card, and low expectations.
I'm not sure I have this right, but thinking Jacksonville beats Tenn, wins the South... Cleveland beats Jacksonville, and comes here. Ravens should win that game, and I'll expect them to win that game. But it's not hard for me to envision that being a fight.