For two-and-a-half seasons, he’s been the barometer.

His face is telltale, broadcasting the ups and downs in the Boston University men’s hockey team. When things are going well, Pete MacArthur’s like an electrical current with a Red Bull. When things are bad, his body language looks like he’s either lost a game or a foot.

After last night’s 2-2 tie against the University of Massachusetts Minutemen, he jumped between both extremes. His White Line — with Boomer Ewing and Kenny Roche — could have scored five times by coach Jack Parker’s estimate in one of the most aggressive offensive charges of the year. The line’s two goals, MacArthur’s fifth of the year and Ewing’s first, showed the potential brilliance the trio could, and must, deliver this year.

But the end result, which MacArthur made clear in a few short words, was unsatisfying — another Terriers’ tie in their fifth straight game with two goals or less. “We tied, so I don’t feel that good,” MacArthur said. A minute later, he was laughing with Ewing about their goals.

It’s the confusion that’s all around the hockey team these days. Things aren’t terrible: Far from it. BU has only one loss in its last eight games, which include four ties. But they’re not great either, with the lack of scoring weighing on their minds.

If the scoring drought is to end, the relief will need to come from MacArthur’s line, which played together all last season. They’re by far the most proven line, with 184 total points between them, and represent the three top returning scorers from last season — Roche (17 goals), Ewing (16) and MacArthur (14).

“We’ve been playing hard, playing pretty well,” MacArthur said. “When the puck doesn’t go in and you play well, your mind plays tricks on you. It makes you feel like you’re not doing your best.”

“Being juniors now, we do have leadership,” Ewing said. “We should be scoring.”

That track record also places them squarely under the spotlight, marking them as the offensive pace car. There’s a good chance nobody takes that responsibility as close to heart as MacArthur, which can both lift and drag.

He’s gone on scoreless streaks before. Long ones. Marathon ones. Last year, he spent the first 17 games with only three goals, including a seven-game absence from the scoreboard.

Not that it makes it any easier this time around.

“I think, psychologically, he needs that to feel like he’s contributing,” Parker said about MacArthur. “He’s tired of me telling him ‘Hey, you’re playing hard, keep it up and the goals will come.'”

Now here’s the strange part.

Not only is MacArthur’s face a barometer for the team’s success, but his goals seem to advertise pretty well too. Last year, BU won 11 of the 12 games in which he scored a goal. During the 11-game win streak from early January to mid-February, he scored seven times.

Correlation doesn’t imply causation-they’ll tell you in stats class. But it doesn’t rule it out, either.

“He knows he’s responsible to score goals for this club, like Roche is responsible,” Parker said. “We’re not looking for [sophomore Steve] Smolinsky to get us a hat trick tonight. We gotta have these guys step up for us. They feel like they’re shirking their responsibility, but they’re not. They’re playing so hard, it just hasn’t happened for them yet.”

The positioning of the line has been fine. So has the effort, Parker said. The timing’s improving, and the opportunities have been growing. And after Kenny Roche came back from his healthy scratch against Harvard, he’s looked as strong as anybody.

So the battle now becomes an internal one, at least until the goals start coming and the room starts buzzing again.

“It’s just hard work and not thinking about it,” MacArthur said. “You feel a hell of a lot better about yourself when the puck’s going in. Coach actually feels bad for us that the pucks aren’t going in. Jason Lawrence doesn’t have a goal yet, and he’s been one of our best forwards every game.”

As always, there’s no better time to break out than against Boston College.

Last year, the Terriers scored more than two goals in only one of the seven games leading up to the opening series with BC. They lost the first game, 2-1. The next night at Agganis Arena, they scored four unanswered goals in the third period.