Cassel took over the next season as head coach.
And last year, Seneca again won the state Group 3 crown.
Yet the only returning starter is senior Cam Bahr, who hit cleanup last year as the designated hitter and now bats third and plays first base.
It's doubtful that any other team has experienced such drastic turnover, but the Golden Eagles are more than hanging in there, although they haven't escaped the periods of inconsistency that accompany a team with such little experience.
Seneca entered the weekend 5-8. In one four-game span, the Golden Eagles won by two, lost by 15, won by 10, and lost by 10.
Those are some fairly significant swings.
Last season's state title was led by righthander Kevin Comer, who eventually signed for $1.65 million after being drafted 57th overall by the Toronto Blue Jays.
Yet even that team experienced plenty of ups and down until Comer got healthy before the state tournament and went 5-0 in the postseason.
Cassel is working just as hard this year as he did last season and any other one. The results have changed, but the work ethic hasn't.
"I enjoy the challenge just as much as last year," he said.
The Golden Eagles' top three pitchers are juniors: Greg Santora, Matt Gall, and J.J. Morrow. Santora leads the way with a 3-2 record.
And Bahr, who will attend Division III McDaniel in Maryland and play baseball, has paced the offense. He concedes that the transition has been difficult, but he is encouraged by this work-in-progress group.
"We're getting more consistent each game," he said.
Bahr has been a model of consistency. He entered the weekend batting .483 with five doubles, one home run, nine RBIs, and a .583 on-base percentage.
"We haven't been able to put it all together, but when we don't make mistakes, we're a very competitive team," Bahr said.
With less than a month to go before the state tournament, the Golden Eagles still have time to work out some of the rough edges.
"It has taken time to jell, but I think we can surprise people," senior catcher Jason Renna said.
Bahr says the run to last year's state title was something he'll always cherish, but for now, he's looking only ahead.
"We have to keep picking it up," he said.
There have been small steps forward, some larger ones backward, but the Golden Eagles are learning on the fly. And as they showed in Tuesday's 12-6 win over Camden Catholic, they have an offense that could be dangerous in the postseason.
Refinement is still needed, but the Golden Eagles have time. So the players and Cassel believe in themselves and don't worry about the total makeover needed this year. This is a team that looks at things as building from week to week and not rebuilding from season to season.
Contact Marc Narducci at 856-779-3225, firstname.lastname@example.org or @sjnard on Twitter. Find his Rally columns at www.philly.com/narducci