Speaking up for what’s right isn’t always easy, especially as a teenager among peers.

But, for Mundelein star forward Sean O’Brien, doing so suddenly became a big part of his job on the team. He knew he had no other choice than to make his voice heard.

“I knew I had to step up as a leader, but sometimes it’s been a struggle,” O’Brien said. “You care about what your teammates think of you. You don’t want to get on their case too much and get them mad at you. But at the same time, I knew I had to continue to speak up.”

O’Brien was thrust into the role of Mundelein’s primary leader this season when standout guard Robert Knar, the team’s vocal leader in previous seasons, went down with a serious knee injury in an AAU game at the end of last summer. Word was that Knar would be missing the majority of the upcoming season, and as it turns out, he was out until mid-February.

O’Brien knew at that moment back in July that the leadership torch had been abruptly passed to him, not to mention the pressure of being the team’s go-to player, also a role that Knar filled.

“It was the first time I was ever put into a role like that, with the leadership, and with being in a position where I couldn’t afford to have a bad game,” O’Brien said. “I knew I would have to be ready (to produce) every game. I knew I would really have to step up as a leader.

“I decided to embrace it all, and I think I’ve actually done a pretty good job with it. Sometimes it’s kind of scary because there’s a lot of pressure, but it’s been a good experience for me to be that guy that the rest of the guys on the team look to, especially at the end of games. I kind of like it.”

What’s not to like?

O’Brien was already putting up big numbers over his career as a starter since his sophomore year at Mundelein. But this season, as a senior, he’s taken his production and influence to a different level, which is a big reason O’Brien has been named the honorary captain of the 2013 Daily Herald Lake County all-area boys basketball team.

O’Brien, who led Mundelein to 18 wins and a spot in the Waukegan sectional semifinals, is averaging a double-double. He scores 21 points per game while pulling down 11.1 rebounds per game. In his spare time, he dishes out 6.1 assists per game, and rolled up an eye-popping 17 assists, a career-high, in a regular season game against Wauconda.

Five times this season, O’Brien has turned in triple-doubles.

“The numbers that Sean has put up this season have been incredible,” Mundelein coach Dick Knar said. “It’s one of the best seasons of a kid I’ve ever coached. We’ve won three straight regionals now and that’s never been done here before. Sean is a big reason we’ve had that success. He’s so multi-faceted and the fact he is able to do so many different things makes us that much better.”

Just like his new leadership role, O’Brien’s versatility was kind of forced upon him.

As a kid, O’Brien grew up playing point guard. And he was good at it, too, handling the ball with ease, and making spectacular passes that few young feeder players could match.

But then O’Brien began to grow. And he went from being averaged-sized in junior high to one of the tallest player on his team by sophomore year at 6-foot-4. He is now 6-7.

The Mustangs have needed O’Brien to be able to take advantage of his height inside, so he has. He’s learned how to bang inside for position, and fight for rebounds.

Meanwhile, he’s kept working on his guard skills so that he’s able to pull larger defenders outside and beat them off the dribble.

“My whole game growing up was about being a point guard and passing the ball. My favorite player was Jason Kidd,” O’Brien said. “I loved his game and the way he found his teammates.

“I still try to do that, but now, I’m also trying to score more and rebound more. I’d say one of the biggest changes to my game is my rebounding. I really take a pride in that now. I think it shows how tough you are.”

O’Brien was as tough as nails over the holidays when he pulled down a career-high 19 rebounds in a tournament game in California. In that same game, he also popped for 25 points, just 3 shy of his career-high, and he racked up 11 blocks. Against Libertyville this season, O’Brien again filled the stat sheet with 18 points, 14 rebounds and 10 assists.

“The transformation of Sean into our No. 1 go-to player came pretty easily,” Knar said. “I kind of felt like we had two No. 1s at the end of last season and over the summer in him and Robert anyway. It was kind of like pick your poison with those two.

“Sean was already capable of taking over games and being the focal point. The only difference now is that he’s doing it all the time. I think that part has been great for him because the responsibility of having to get the job done day in and day out is a mindset that you have to have in college. I think this experience is going to help Sean next year.”

Back in the fall, O’Brien signed early with Southern Illinois, which has struggled this season with a first-year coach. Knar believes that the path in Carbondale could be clear for a player like O’Brien to come in and make an immediate impact as a freshman.

“I can’t wait to get to Southern,” O’Brien said. “I need to put on more muscle and get stronger. But I think if I keep working hard, I could play a lot right away.”

After this season, O’Brien is prepared to do much more than that, if necessary.

“Getting this year of experience under my belt of being the leader and the go-to player on my team could really help me,” O’Brien said. “I could be in that role again someday.”