Since the St. John’s Prep football team last played a game on home turf at Cronin Memorial Stadium, it has gone through an interesting series of ups and downs.The up came when the Eagles upset top-ranked Everett. But the downs have also come with the good as the Prep lost to Brockton five days later and then, last Friday in Dracut, did everything but put the Middies away.Despite over 300 rushing yards, penalties and turnovers were a killer for the Prep in a 28-20 loss.”We’ve gone against good teams and a couple mistakes here and there make the difference,” Prep coach Jim O’Leary said. “It came down to four plays against Dracut. We made some mental mistakes and they capitalized on them.”One would think that coming home, the Eagles (4-2) would catch a break on their schedule with a bye week on the horizon before Catholic Conference play begins.Guess again.On Saturday, the Eagles host a St. John’s (Shrewsbury) team that is undefeated and is the defending Division 1 Central Mass. Super Bowl champion.”It’s hard to be undefeated at this time of year and they’re on a roll right now,” O’Leary said about the Pioneers. “We know we’re in for a dogfight.”The Eagles have found success against their fellow Xaverian Brothers school in recent times, besting Shrewsbury last year. Two years ago, the Prep had a big lead in the fourth quarter before the Pioneers rallied to win.”It’s another one of those games where we can’t afford to be in negative turnovers,” O’Leary said.Danvers at BeverlyAt Hurd Stadium (2:30), the Panthers come in off arguably their best performance of the season in last Friday’s 20-point win over Peabody.Running back Rashad Sims was the star, earning Item Offensive Player of the Week honors for his 229-yard, four-touchdown performance. Quarterback Mark Hannable threw two touchdowns and will face a Danvers team coming in off a loss to Classical last Friday.