Coaching college football at the FBS level is not the kind of job that offers much long-term security. Don't get me wrong, for the most part, the money's great. In fact, salaries increase every single season, but there's another side to that coin. With more money at stake, schools are no longer as willing to accept struggles or bumps in the road.

More than ever, being a college football coach has become a "what have you done for me lately" vocation.

So as we head into spring practice this year, there are plenty of coaches feeling some heat and added pressure to put together a strong season in 2018. In this week's Friday Five, as I've done during the last three offseasons, I'm ranking the five coaches on the hottest seats in the country heading into the 2018 season.

We'll start in Ann Arbor.

5. Jim Harbaugh, Michigan: I'm putting Harbaugh here, but I'm stretching the definition of hot seat a bit while doing so. Jim Harbaugh isn't going to get fired at Michigan this year unless something goes horribly wrong, either on the field or off it. The reason I include him on this list, though, is that the tide has started to turn a little bit.

When Harbaugh returned to Michigan, he was seen as a conquering hero. The prodigal son returned to restore a proud program to its place among the greats. Well, we're three seasons in now, and Harbaugh's Wolverines have gone 28-11 and 18-8 in the Big Ten. After a couple of 10-win seasons to start, things went backward last year, as Michigan finished 8-5 and in fourth place in its division.

In fact, Michigan is yet to finish higher than third in the Big Ten East.

While there are plenty of valid reasons for the step back last season, the fact of the matter is Harbaugh needs to start showing more positive results on the field. While he grabbed most of the attention in recent years, it's been James Franklin at Penn State that has been the one to provide a challenge to Ohio State for supremacy in the division. Michigan needs to make a clear step forward in that department itself, or the natives will get restless.

4. Derek Mason, Vanderbilt: Things were trending in the right direction going into the 2017 season. Mason's Vandy teams had improved in each of the last two seasons, reaching their first bowl game under Mason after a 6-6 regular season in 2016. But then 2017 came, and in a year in which the SEC East was an utter crapshoot behind Georgia, the Commodores regressed, finishing 5-7 and only 1-7 in the SEC. Sure, that one win came against Tennessee, which always feels good, but those positive feelings only carry so far.

I don't want to say it's "bowl game or bust" for Mason in 2018, as he did receive a contract extension recently, but if there isn't a noticeable step forward in Year Five, then Vanderbilt could look to make a change.

3. Kalani Sitake, BYU: Things took a major turn for the worse in Sitake's second season at BYU, as the Cougars followed up a 9-4 campaign in 2016 with a 4-9 record last year. And while losing is one thing, it's taken to another level entirely when your offense is putrid.

And BYU's offense was rather odorous in 2017, averaging only 17.1 points per game (and 8.2 PPG in its six games against teams that finished with a winning record).

Making matters worse for Sitake is that Navy's Ken Niumatalolo sure has shown a lot of interest in leaving Navy lately. Just this past offseason, it looked as though Niumatalolo was destined for Arizona before a change of heart (on which side isn't clear). If BYU struggles again in 2018 and Niumatalolo continues to succeed at Navy, there will be plenty of voices calling to bring Niumatalolo -- a Mormon -- to BYU.

2. David Beaty, Kansas: Nobody thought David Beaty was going to step into the Kansas job and immediately turn things around. It's one of the most difficult Power Five jobs in the country for a variety of reasons.

The problem for Beaty is that, as he enters Year Four, there haven't been any signs of progress yet. The Jayhawks are 3-33 in his three seasons, and that includes a 1-26 record in the Big 12. The school has recently made a large financial commitment to improving its football facilities, and it looks like Kansas is ready to do what it has to do to improve its football program.

Another winless season in the Big 12 might mean finding a new coach is another step in that process.

1. Kliff Kingsbury, Texas Tech: This is an odd situation to get a read on, because if Kliff Kingsbury wasn't Kliff Kingsbury -- a beloved Texas Tech alum seen as a savior upon his arrival -- I'm pretty sure he'd already been replaced in Lubbock. So I don't know how long the leash truly is, but the fact of the matter is that things have not gone according to plan.

In Kingsbury's first season at Texas Tech in 2013, the Red Raiders went 8-5 overall and 4-5 in the Big 12. Things haven't been that good since.

There have been only two bowl games in the last four seasons, and last year's came because of a win against Texas to finish the regular season. Through five years, Kingsbury has gone 30-33 overall and 16-29 in the Big 12. I just don't think that's what Texas Tech is looking for.

Now, if there's good news, it's that the Tech defense seemed to be trending in the right direction last season. If that side of the ball takes another step forward, it should lead to major improvements for Tech because we know the offense will be fine. It always is.

But if the defense doesn't improve, it might be time for Tech to find somebody who can get the job done.

Honorable Mention: Mike MacIntyre, Colorado; Scottie Montgomery, East Carolina; Barry Odom, Missouri; Ed Orgeron, LSU