Really no doubt as to who the Catcher will be to start the 2007 season, and really no doubt who will remain the Catcher, barring any injuries.
Varitek will start
Mirabelli will back up and be Wakefield's personal Catcher
George Kottaras will be the 3rd option, starting the season in AAA
The Catcher position is no longer an offensive position for the Red Sox. Defensively, it is still very sound. However, Sox Catchers are not the most feared by baserunners. But who is? What's important is that Tek calls a good game, and Mirabelli follows the knuckle ball well.
But there's minimal production out of this duo. Tek will be turning 35 in a few weeks, which is 65 in Catcher's years. He still does a good job, but like most Catchers at this stage in their careers, his bat is not what it used to be.
Last season he hit .238, with an OBP of .325. He hit 12 HRs, his lowest total since 2002. Although his ABs were very limited, he managed to slug .400, just barely. I'm not saying he's a hole in the lineup, I'm just saying he is no longer a consistent offensive producer like he was a few years ago.
My completely non-scientific and totally incorrect forecast for Varitek in the '07 season is a .230 average, .310 OBP, .380 slugging, 10 HRs, 60 RBI. He'll probably hit the DL or miss time with an injury at some point, hopefully not for an extensive period.
Mirabelli struggled mightily at the plate last season. He'll start off as the 2nd Catcher, but his job is not secured, not yet at least. He hit .193 with the Sox last season, and .191 in between Boston and San Diego. He did hit 6 HRs, which is good for a backup Catcher, but he also struck out 54 times in 161 ABs. That's a K every 2.98 ABs. For reference, Wily Mo Pena struck out once every 3.07 ABs last year.
Mirabellie has a job now, but Wakefield's position in the rotation is not a sure thing. With Papelbon, Schilling, Beckett, and Matsuzaka, Wakefield is definitely the 5th starter. And Jon Lester might not be too far away. Wake is also versatile so he might be shipped to the bullpen. If this happens, and Mirabelli is struggling, it will be time for Kottaras to be called up.
Kottaras didn't have amazing numbers in AAA last year, but he's got potential. He'll be the Catcher in Pawtucket to start the season. He's also caught knuckleballer Steve Sparks before, so he is a good option for a 3rd Catcher.
All in all, Catcher is not a hole. It isn't going to give us much production, but few Catchers really do. Varitek's value is with the pitching staff. He'll add a few RBI here and there, too. But I see him and Mirabelli either batting 7th, 8th, or 9th and no higher. They'll probably spend most of the season at 8th and 9th.