But Jansen, who came up in the sport with Portland's legendary Team Quest gym, has a recognizable quantity of old-school toughness.
So even though Brooks retained his Bellator lightweight title in their main event fight, he had to work for it. Brooks turned up the heat over the final two rounds to put away the fight against his tough-as-nails foe, winning by unanimous decision. The judges' scores were 49-46 across the board.
"Dave Jansen showed his warrior spirit tonight," the American Top Team fighter said. "I hit him with some hard shots and I thought I was going to break my hand."
Jansen (20-3), who entered the bout on a seven-fight win streak, came out fast in an active first round, keeping the champion backpedaling with a high-volume output and getting the best of things in the clinch.
Brooks (16-1) picked up the pace in the second round, as he fired off body kicks with both legs, then closed the distance and landed solid flurries. The third round was more of the same, but both fighters appeared to be running out of stream.
The champ, though, seemed to find his second wind in the championship rounds., He battered the Portland native in the fourth round, leaving him bloodied and bruised. Brooks continued to push the pace in the closing round, and while Jansen remained tough, he wasn't able to do anything to turn the bout in his favor.
"I'm on my way," Brooks said. "I'm judging myself the hardest, going to continue to try to get better."
Popular kickboxer Joe Schilling got the loudest reception of the evening heading into his co-feature middleweight bout against Rafael Carvalho, but Carvalho played the role of spoiler, scoring a split decision victory.
Carvalho got judges' scores of 30-27 and 29-28, while Schilling took a 29-28 card. MMAFighting.com scored the bout 29-28 for Carvalho.
Schilling's kickboxing credentials are world class, and his striking has translated well in MMA, as he proved with a memorable knockout of Melvin Manhoef in November. But Schilling, in his sixth pro MMA bout, seemed determine to prove he's become well-rounded in MMA, and it backfired, as Carvalho was only too willing to oblige.
Schilling held his own in the first round, which he won on two judges' scorecards, but, by the second, Carvalho took over the tone of the fight by exploiting Schilling's MMA inexperience. He controlled the second round in the mat after Schilling brought him there with a guilotine, transitioning out and then nearly submitting him with an armbar.
In the third round, Schilling wobbled Carvalho with a jab, but Carvalho regained his bearing and controlled the remained of the round on the ground.
Carvalho, of Rio de Janeiro, improved to 11-1, with 10 straight wins. Schilling dropped to 2-4.
In a lightweight fight, Poland's Marcin Held added to his reputation as one of the sport's top up-and-coming submission artists, as he added Tiger Sarnavskiy to his list of victims. The 23-year-old Held verbally submitted Sarnavskiy (30-3) via kneebar at 1:11 of the third round.
The bout was primarily a grappling contest, and primarily consisted of Held working for submissions, whether working from the top, the bottom, or from side control. Sarnavskiy escaped several times, but he had no answer early in the third, when Held transitioned into a tight kneebar.
The victory was Held's 12th career submission victory, as he improved to 21-5 with 11 wins in his past 12 fights. After the bout, Held said he's ready for a crack at Brooks' title.
"It's a great thing, I was trying it in the first round, I was keeping pretty busy, and then in the third round is when I got him," Held said. "Yeah I'm sure I'll be getting him in the fight. I think I'm ready."
Unheralded Tony Johnson scored an upset victory over former Bellator heavyweight champion Alexander Volkov. Johnson (9-2), an American Kickboxing Academy fighter, used his clinch work and wrestling to overpower the surprisingly listless Volkov (24-5). Johnson tired in the third round and Volkov had his best round of the fight, but it wasn't enough.
Two judges scored the bout 29-28 for Johnson and the third an inexplicable 29-28 for Volkov, who lost for just the second time in his past 17 fights.
In an undercard bout of note, veteran sluggers Joey Beltan and Brian Rogers went toe-to-toe for 15 minutes in a fun brawl. The scores were all over the map, with a 28-28 card to go with 29-27 and 29-28 for Rogers as he took a majority decision. MMAFighting.com scored the bout 28-28, giving Rogers rounds one and three and Beltran a 10-8 second.
Rogers withstood an epic beatdown over the final minute of the second round, but managed to get to the end of the round. The scoring, then, came down to close calls in the first and third.
Beltran (16-11, 1 NC), an Alliance MMA fighter who has fought as high at heavyweight in his career, was making his middleweight debut. He won for the second time in his past three fights. Ohio's Rogers (11-8) has dropped four of his past five.