Shannon Murphy is a force in the paint for the Watertown High girls’ basketball team. The 6-foot senior forward can compete on the glass with any other girl in the state, she can handle the ball, and she delivers solid D.

But the key to success for the Raiders is that the Holy Cross-bound Murphy (12 points, 8 rebounds per game) is not a solo act.

After last year’s march to the Division 2 state final against Longmeadow, the Raiders (11-2) are off to one of the best starts in program history. And after the graduation of six seniors, they have done so by sharing the ball.

Watertown is not alone. The same applies to the girls’ varsity squads at Newton North and Newton South, along with Wellesley, Hopkinton, Waltham, and Wayland.

They have bought in to the premise that building a squad that can count on any number of players is a key to success. And building a team that way helps players feel more comfortable and thus play with more confidence.

Newton South’s Veronica Burton is averaging 20-plus points per game. Weston’s Sophia Guerrier and Christina Costa are each at 17-plus points, and Darby Leid is at 15 ppg.

Watertown graduated a great deal of skill and experience. Early on, that forced this year’s team to learn that it would need to forge its own path.

“We’ve seen firsthand that every class is different and we have to adjust to each new grade coming in and old grade leaving,’’ junior Lauren Petrillo said.

“It’s most important to create our own identity with each class.’’

Added classmate Cali McMahon: “We can’t rely just on the seniors because they’re not going to be here next year so we have to set the standard for how we want it [for ourselves].’’

With a team looking to create a longstanding tradition of success, the system is a big factor.

That has been the focus for Mo Hamel, in her first season as the head coach at Newton North.

Fortunate enough to have a trio of seniors — including Florida State-bound guard Sayawni Lassiter — she knows that she has to look to the future as well as the present.

“We want to have a system in place that will help us have success for years to come, and that players can fit themselves into and we don’t need one particular player to solve all of the problems,’’ she said.

That system, however, needs to be open to evolution.

For Watertown coach Patrick Ferdinand, the system put in place also presents a challenge.

“The biggest challenge . . . sometimes is getting kids to fully buy into what your system and style is for that particular year,’’ he said.

“Every year, people will ask me how we are going to do this year and I just have to say I don’t know. . . . It really comes down to kids doing their role as best they can.

“Being able to plug yourself into a role and when it [comes] time for that challenge to be put in front of you, can you accept it? . . . When teams take things away from you, you have to have trust in your teammates that they’re going to make the right choice.’’

The underlying theme: how each individual player ultimately meshes into a cohesive unit. When done well, it can become the catalyst in making a successful team run.

“We don’t really rely on anyone,’’ Watertown senior Hanna McMahon said. “As a whole, we work together as a group.’’

Added her twin sister, Jenna: “Everyone has different roles that they use in order to be successful.’’

For Murphy, that team-first approach is a pressure release.

“If you’re not the one scoring the points, you’ll be the one rebounding the ball or passing the ball. And I think having a team that can do a little bit of everything makes everyone else’s lives easier.’’

As the final weeks of the season begin to set in, it has become a time of reflection for the seniors. They’ve made the program their own, and now they are seeing what they can do with it as the state tournament rapidly approaches.

At Watertown, the Raiders have already exceeded the expectations of those who felt that there would be a slide with the heavy graduation losses.

“We had a lot of people expecting us to struggle a lot more than we have in past years, and I think we’ve been proving everyone wrong. We’ve done a good job living up to the expectations of past years.’’

And in having so much success in the final season, it’s allowed Murphy and the other seniors to appreciate the past four years.

“Not just me,’’ Murphy said. “But I think everyone has just been extremely lucky to have had so much success throughout their high school careers.’’

Logan Mullen can be reached at logan.mullen@globe.com.