The mathematics being performed by the Phillies in the coming weeks and months is going to involve only addition, subtraction, and multiplication.

The degree of difficulty, however, must seem more on the level of advanced calculus for general manager Ruben Amaro Jr. and his team of decision makers.

Perhaps the most complicated problem of them all will be at catcher.

What to do about Carlos Ruiz?

This dilemma is a reflection of just how fast the game of baseball can change. When the season opened, Ruiz was serving a 25-game suspension, but the Phillies were confident about their catching situation.

Amaro acquired Tommy Joseph from the San Francisco Giants for outfielder Hunter Pence at the trade deadline last summer, adding him to a mix that already included Sebastian Valle and Cameron Rupp in the minor-league system. Joseph, who served as an understudy to Buster Posey during a couple of spring trainings with the Giants, shot up the team's prospect chart and was clearly at the head of the Phillies' catching class.

Now, after suffering a concussion in early May, the 21-year-old catcher is trying to clear his head and get his game back. All we know about his big-league future is that it doesn't appear as if it is going to begin this summer or next spring. That is an issue because Ruiz's contract expires at the end of the season.

"We didn't necessarily think that Joseph would be ready in 2014," Amaro said. "At some point in the year we thought he might be, but obviously the concussion is an issue for him and it has slowed down his progress. We still think he is going to be an everyday catcher, but we can't count on him for next year."

Rupp, 24, is the prospect closest to the big leagues at the moment because he's getting the majority of playing time at triple-A Lehigh Valley after opening the season at double-A Reading. There's no sense that the Phillies would be comfortable with him as their starter next season.

Meanwhile, the fact that Rupp got the call over the 22-year-old Valle is an indication of how the Phillies see the pecking order. Valle has not helped his own cause. He entered the weekend hitting .223 with seven home runs and 20 RBIs.

The Phillies love Erik Kratz as a backup, but probably would not love him as much in a starting role.

All of that is what makes Ruiz's situation more difficult than any other on the roster, including that of second baseman Chase Utley, the team's most iconic player.

If the Phillies want to part with Utley, they at least have Freddy Galvis and Cesar Hernandez ready to replace him.

Amaro's first choice to be the Phillies' 2014 catcher remains Ruiz, and that would be the best choice.

"We want to figure out how to keep him long-term," the general manager said.

He would not say if the Phillies have had any talks about a contract extension for the catcher, but a baseball source indicated no such discussions have occurred.

Ruiz, 34, is in the final year of a four-year deal worth $13.35 million. He is being paid a career-high $5 million this season.

So what's he worth beyond this season? What could he bring back in a trade? What would the Phillies do if he went elsewhere?

Figuring out a contract for Ruiz is difficult. He'll be 35 at the start of next season and he has played in only about a month's worth of games this season because of the suspension and a subsequent hamstring injury. The suspension for using Adderall is obviously another consideration.

Ruiz entered the weekend with zero home runs and six RBIs in 110 plate appearances, but a year ago he was arguably the team MVP.

The Detroit Tigers and Cincinnati Reds are two contending teams in need of catching help, so if the Phillies can get some young arms for Ruiz, it would not be an awful idea to trade him.

Amaro made the point that he can re-sign his own potential free agents even if he trades them before the end of this month.

A possibility to replace Ruiz if he went elsewhere would be the guy catching for the Atlanta Braves this weekend at Citizens Bank Park. Brian McCann can also be a free agent after the season. He has hit 20 home runs or more in six of his last seven seasons. Despite a late start this season because of shoulder surgery, he already had 10 homers in 149 at-bats entering the weekend. He's only 29 and, like Ruiz, is considered a positive influence in the clubhouse.

It would probably take huge dollars to sign McCann, but money should be no object for a team whose general manager says they should be built to contend every season.