NASHVILLE, Tenn. -- Much has gone wrong for the Kansas City Chiefs during this unexpected 2021 NFL season. After a 27-3 loss to the Tennessee Titans on Sunday dropped them to 3-4, their chances for a fourth straight trip to the AFC Championship Game or a third straight berth in the Super Bowl appear remote.

What's happened? Here are some of the things that are ailing the Chiefs:

It's not business as usual for quarterback Patrick Mahomes. Mahomes has at least one turnover in each of the past six games and multiple turnovers in each of the past three. Some of his interceptions have come on passes deflected by a Chiefs receiver, but Mahomes is hardly blameless. He's tried to force passes into coverage and has thrown interceptions instead of merely trying to avoid a sack. Mahomes said after a game against the Buffalo Bills two weeks ago that he would reevaluate his decision-making process in light of the turnovers. If he has, it hasn't shown. Against the Titans on Sunday, he posted a 6.1 QBR, by far the lowest of his career. His previous low was a 37.4 in Week 7 last season against the Broncos. Is this fixable? Mahomes entered the season with a touchdown-to-interception ratio of almost 5-to-1. He hasn't been turnover-prone during his career, so he is capable of being more secure with the ball. He has to quit forcing throws, something he might not do given how quickly the Chiefs' defense gives up points, though.

The Chiefs have a talent shortage on defense: Since rebuilding their defense following the 2018 season, the Chiefs have invested mainly in offensive players. Their first-round draft pick in 2020 was a running back, Clyde Edwards-Helaire. They traded their 2021 first-round pick for an offensive tackle, Orlando Brown. Their big-money free-agent signing this year was a guard, Joe Thuney. In all, between the draft, a trade and free agency, the Chiefs acquired six offensive linemen and left the defense mostly intact. The Chiefs have just two former first-round draft picks on defense, neither one drafted by Kansas City. Those players, cornerbacks Mike Hughes and DeAndre Baker, were discarded by their former teams for little or no return. Three recent defensive picks in the top three rounds, defensive linemen Breeland Speaks and Khalen Saunders and linebacker Dorian O'Daniel, haven't been worth the investment. Is this fixable? Not this year. The Chiefs will have to ride with what they have.

Their pass rush has been punchless: The Chiefs have invested heavily in one area on defense in recent years, and that's on the defensive line, where Chris Jones and Frank Clark play. But both have been limited this season by injuries and aren't producing when they do play. Jones missed two games and hasn't had a sack since getting two in the season opener. Clark missed three games and doesn't yet have a sack. The Chiefs had one sack against the Titans. They had seven entering the game, their fewest through six games since 2011. They were 28th in ESPN's Pass Rush Win Rate, beating their blocks within 2.5 seconds just 34% of the time. Is this fixable? With Jones, Clark and other complementary players, the Chiefs should pressure the quarterback far better than they do. But if it hasn't happened through seven games, it's unlikely it will happen this season.

The offensive line investment hasn't consistently paid off: The Chiefs have mostly protected Mahomes better than they did against the Titans. But the Tennessee game was a bad one. Tennessee blitzed just once in 44 dropbacks, but he was still pressured 18 times. Opponents have blitzed Mahomes just 13% of the time this season but pressured him on 35% of his attempts. Brown, who played mostly right tackle before being traded to the Chiefs by the Baltimore Ravens, is trying to establish himself as a left tackle. He's had moments when he's played well, but he played poorly against the Titans. Is this fixable? The Chiefs, who start two rookies and two other linemen who weren't with the team last year, should get better as the season goes along.

So, can the Chiefs make the postseason? The Chiefs, at 3-4 but with five divisional games remaining, are still a part of the AFC West race. The problem for them, as it's been all season, is not their record or divisional standing but the way they're playing. They could get into the playoffs, but they won't without making some major improvements in these areas and others.

The Chiefs have played a rugged schedule. Five of their seven opponents are strong playoff contenders.

But things don't get much better in that regard. Three of their next four opponents -- the Packers, Raiders and Cowboys -- are in first place in their respective divisions.

It's up to the Chiefs to fix the problem. They've shown little in the first seven games to suggest that will happen.