SANTA CLARA - - When the horn sounded Thursday morning to mark the beginning of position drills, the 49ers’ linebackers were enthusiastically greeted by a hopping, hand-slapping player in a blue uniform.

Kwon Alexander returned to the practice field after missing two months following surgery to repair a torn pectoral, and even players at other positions can feel Alexander’s overflow of positivity.

“He’s probably the MVP of our team,” 49ers rookie defensive end Nick Bosa said earlier this week. “He’s the energy, all the time. It’s kind of hard for 16 games, every single day, to bring the passion and have fun with it. And if he’s there, then we have no choice but to have fun.”

"He’s the emotional leader of our team," rookie linebacker Dre Greenlaw added. "He’s the hype guy that gets everybody going and we definitely missed that.”

The 49ers targeted Alexander, who was coming off a torn ACL, at the outset of free agency last year over every other available linebacker. The 49ers felt Alexander would fit in perfectly to what they were building on defense.

San Francisco needed someone who could bring some attitude and big-play ability to a defense that lacked any kind of ability to change a game in 2018. The 49ers signed Alexander to a four-year, $54 million contract in March.

“That’s why they brought him here,” Bosa said. “That’s why they paid him. I started to learn early in the year how important he was. And then we lost him and everybody had to try and step up. But getting him back is going to be a boost for all of us.”

Alexander started the first eight games of the season at weakside linebacker. He registered 34 tackles, a half-sack, an interception, four passes defensed and a forced fumble. When Alexander was on the field, along with edge rushers Dee Ford and Bosa, opposing offenses did not have a chance.

But Alexander was injured on Oct. 31, against the Arizona Cardinals when he reached out with his left arm and dove to trip up running back Kenyan Drake for a tackle late in the third quarter.

At the time, Alexander was expected to be out for the remainder of the season. But, now, it appears he has a legitimate chance to play in the postseason if the 49ers advance past their divisional-round game next Saturday. He will be watching J.J. Watt of the Houston Texans, who's returning from the same injury this weekend on a similar expedited timetable.

In Alexander’s absence, Greenlaw stepped in and started the final eight games of the regular season alongside middle linebacker Fred Warner.

Alexander was there to guide Greenlaw every step of the way.

“Kwon is one of those guys, he just tells you how it is,” Greenlaw said. “That’s it. If you do it this way, this is how it’s supposed to be.

“There is no gray area. ‘Hey, you have the A-game, go plug it.’ I tell him, ‘Sometimes I see this and this.’ ‘No, go plug it.’ So at the end of the day, that’s the type of guy that he is.”

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Greenlaw benefited from Alexander’s teaching and influence. His confidence and knowledge of his assignments showed when the 49ers needed him most.

Greenlaw made the biggest defensive play of the season on a fourth-and-goal tackle of Seattle Seahawks tight end Jacob Hollister just inches short of the goal line in the final seconds of Week 17. Greenlaw’s play preserved the 49ers’ 26-21 victory, clinching the NFC West title and homefield advantage in the playoffs.

“He’s been legendary, man,” Alexander said of Greenlaw, using his favorite descriptive word. “He’s been a great rookie. He stepped up tremendously. I’m proud of him. He’s put the work in, and you can see that on the field.”