Last week, I outlined why Jeremiah Attaochu might be the X-factor on the San Francisco 49ers defense. George Kittle fits that bill on the offensive side of the ball.

The second-year tight end could be poised for a breakout campaign in 2018. There are two obvious factors in this equation: health and opportunity. Kittle played in 15 games as a rookie (seven starts), catching 43 passes for 515 yards and two touchdowns. He posted his first 100-yard game in Week 17 against the Los Angeles Rams.

Kittle's highlights were mixed with the inconsistencies typical of an NFL rookie. The first-year learning curve played a part in those ups and downs. Injuries were a more significant hindrance. After dazzling in his first offseason program, Kittle's training camp was marred by a lingering hamstring injury. The tight end also never fully recovered from a midseason high-ankle sprain.

"His toughness showed," said tight ends coach and assistant head coach Jon Embree. "He went out there and gutted it out. There were some times in games where he couldn't really put his foot in the ground."

Now with a clean bill of health, Kittle figures to be San Francisco's top pass-catching tight end and one of the team's best options in the red zone. Remember, Kittle's immediate emergence is part of the reason why the 49ers felt comfortable trading Vance McDonald last summer.

Embree called Kittle the best 1-on-1 tight end on the 49ers roster. Kyle Shanahan agreed with Embree's assessment.

"I think George can be a very good tight end in this league," Shanahan said. "It's rare that you have a guy who is built to block very well who also runs in the 4.5's and who is quick enough to separate. I think George was a big part of our team last year."

The concoction of potential mixed with opportunity can yield special results, and Kittle's ceiling cannot be ignored. He's likely to be one of Jimmy Garoppolo's most reliable targets in 2018 and beyond. Many in the fantasy football community are already penning Kittle as a sleeper for the coming year.

Young players are always a bit of a wildcard, but Kittle has already shown to have the right mental makeup to overcome obstacles along the way.

"He is a tough guy who is going to play through things, but he's healthy right now," Shanahan said. "He's moving great and it's allowing him to get better in the run and pass. That'll continue. George has got a lot of ability."

Embree urged that Kittle's understanding of "the why's" will be crucial to his development. He needs to understand his own role, sure, but Kittle also must recognize precisely how it fits into Shanahan's offense as a whole.

Kittle's comprehensive knowledge of the playbook must be accompanied by the tight end's continued good health. Should that come to fruition (knock on wood), then watch out.

"I think if he's able to do that, everyone will be pleased with what he brings to the table for us," Embree said.