Warning: Spoilers through the finale of season six of “24″ follow.

So, “24″ wrapped up with its finale on Monday. It was a by-the-numbers finale to a thoroughly disappointing season — easily this series’ weakest. Given what they’d set up, there was virtually no other way this season could’ve ended. After the finales of seasons four and five, another shocker like the ones that sent Jack off into self-imposed exile or Chinese prison would’ve felt superfluous and false for the sake of needlessly cliffhangering us. It was time for a more dialed-down ending. We got that, at least — not that I liked the outcome.

Jack Bauer in "24"
DAMMIT! Jack Bauer has found himself prisoner to the most mediocre season of “24″ yet.

The rest of the finale’s proceedings followed the plot down the only path available. It offered competent (if routine) action, but not much tension. If you think back to last year’s finale where Jack interrogated President Logan in that riveting multifaceted scene, you realize how far this series has fallen in the past year.

Meanwhile, here’s a question: In how many ways has “24″ jumped the shark this season?

One could argue that the show jumped the shark in the “true” sense of the phrase when the nuke blew up in the season’s fourth episode. “Jumped the shark” used to mean that a point of extreme, over-the-top drama had been reached that could not be topped. The more widespread and current use of “jumped the shark,” however, has come to mean any plot development that is obviously ridiculous.

Under that definition, as my friend Eric mentioned to me in an e-mail earlier this season, “24″ has jumped the shark many times over this season.

Don’t get me wrong. I enjoy aspects of “24″ even when it’s bad. For example, this season had Peter MacNicol, who was a good addition to the cast. But as I said before, this season of “24″ has been a haphazard mess. This was true right through to the end. Aside from Jack, whose motivation always is to Save America and do the Right Thing in the Most Reckless Way Possible, no character has had a motivation that has lasted more than a few episodes before some kind of awkward about-face. Let’s look at the ways in which this season has strained credibility by switching directions in mid-stream.

• Wayne Palmer starts as a man of caution before being blown up, put in a coma, then brought out of the coma, where he then pretends to be a hawk which turns out to be a bluff. Then he collapses from his prior injuries and exits the season, perhaps the series.

• Homeland Security absurdly revokes Nadia’s security clearance at the beginning of the season because she’s Muslim. By the end of the season she’s running CTU. Talk about a policy shift.

• Vice President Daniels starts as an uber-hawk so extreme that he’s willing to be complicit in the attempted assassination of the sitting president. He ends as a self-doubter that is humbled to the point of paralysis. His stones must’ve been vaporized somewhere around Hour 18.

• Philip Bauer disappears for at least a dozen episodes before coming back into the game. He tells the Chinese that he’s had it and is done working with them. It turns out he’s not. This is not a plot twist or a matter of motivation; it’s a purely contrived device to move the plot from A to B. And his death in the finale had a distinct “who cares” effect, having been stripped of all personal meaning between father and son long ago. As Jack aptly puts it, “He was dead to me years ago.”

• Nadia has feelings for Milo (maybe), and then it’s revealed she has feelings for Doyle (maybe) — despite the fact that earlier in the day Doyle suspected her of being a traitor and tortured her for information. This silly triangle results in some of the most inane dialog imaginable regarding would-be relationships. (The writers of “24″ need to stay away from office romances.) Milo ended up with a hole in his head and Doyle at least half-blind, so I guess there won’t be any CTU hook-ups to emerge from this.

• The Russians threaten to attack an American military base and start a war if the Americans don’t recover a component before it falls into the hands of the Chinese. The clock put upon this scenario is totally manufactured by the plot. And the Russians are simultaneously friendly enough that they don’t want to go to war, but enough of a plot device that they are willing to go to war because they must apparently make a strong political statement or risk looking like wimps. How any of this makes sense is beyond me. Also beyond me is how sinking an oil platform provides the proof that is necessary to avert the crisis.

• Audrey Raines is alleged as dead, then captured, then freed, and, ultimately, crazy. It’s a truly thankless role for Kim Raver, who had previously been one of the better female characters on this frequently male-dominated show. In the finale, she has a scene, but no lines. Jack concludes he must let her go for her own sake, which is the hoariest cliche possible in this particular playbook.

• Recycled plot lines from previous “24″ seasons: Granted, some of this just goes with the territory on this show, but we had: Nuclear bombs chased around like MacGuffins, electronic components chased around like MacGuffins; terrorist leaders chased around like MacGuffins; assassination attempts on the president; a scene where the president’s competence is questioned and a vote attempts to strip him of power; Jack Bauer torturing guys for information; Jack Bauer taken into CTU custody more times than you can count; Jack Bauer forgiven and put into the field again and again; the head of CTU forced out; and someone new put in to replace the forced-out CTU head.

The ultimate shark-jumping, however, came in the utterly predictable “revelation” that Chloe is pregnant. Let’s see — she faints in the final seconds of the next-to-last hour, but she’s quickly revealed as okay. This happens while she’s facing a questionable future with her ex-husband Morris. Do the math — what is the only possible outcome here for a previously unexplained medical condition that causes fainting and nausea and maybe ties up as-yet-unresolved romantic subplots?

Yes. An effin’ pregnancy. On “24.” Involving Chloe.

Chloe was vastly underused this season and, when used, used wrongly. What we always liked about Chloe was her anti-social quirkiness and her tendency to buck authority. This season she’s been in the middle of trite relationship spats and friction between Milo and Morris. Bo-ring. Now we have the prospect of Chloe as a mom? Is that something anyone actually wants to see? I have my doubts.

Also, Jack Bauer never got on a plane all season. He got off a plane in the first episode, but I have a new rule: You know something’s wrong with a “24″ season when Jack doesn’t spend at least most of one episode doing something crucial on a plane. Helicopters don’t count.

In interviews, the producers have admitted the weaknesses of this season and their intention to shake things up next year. I hope they do. I will be watching “24″ next season and hope for a return to form. Something different needs to happen. A nuke blowing up is obviously not the answer, because nukes are about consequences, and there’s not enough time in a “24″ day to deal with heavy stuff like that. You get one episode of intense aftermath emotion, but by episode 24, it’s just another day at the office.

Jammer’s “24″ Season Six Rating: ** (out of four)