ARLINGTON -- Free-agent right-hander Ben Sheets was 13-9 with a 3.09 ERA in 31 starts for the Milwaukee Brewers last year.

That's the kind of performance that usually merits a multiyear contract for substantial guaranteed money, especially for a pitcher who is just 30 years old and was the starter for the National League in the All-Star Game.

Sheets also ended the season with a flexor tendon injury that prevented him from pitching in the playoffs. He has been on the disabled list five times in the past four years.

That's the kind of medical history that often requires a free-agent pitcher to settle for an incentive-laden contract.

Although both sides have declined to comment on negotiations, that's likely the crucial issue between the Rangers and Sheets with Spring Training less than two weeks away.

There is no doubt that the Rangers are interested in Sheets, who is from Louisiana and has a home in Dallas. The interest is mutual. But there is also no doubt that the Rangers, like all other teams, have serious concerns about Sheets' medical history. That's easily the reason why he is the most prominent pitcher still available on the free-agent market.

Length of contract can also be crucial. Sheets' agent, Casey Close, likely is looking for a multiyear deal while the Rangers would prefer to do a one-year deal.

But this is more likely going to come down to how much guaranteed money is in the contract and how much must be earned by reaching incentive clauses. The Rangers obviously want significant incentive clauses as protection against injury.

Last year the Rangers signed pitcher Jason Jennings -- also represented by Close -- to such a contract. Jennings was coming off flexor tendon surgery and agreed to a one-year contract with a base salary of $4 million. Another $4 million were available in incentives.

Jennings could have made another $375,000 each for reaching 120, 130, 140 and 150 innings pitched. Then he would have made another $500,000 for 160, 170, 180, 190 and 200 innings pitched. He reached none of those levels. Instead, he made just six starts before having more flexor tendon problems that required surgery and brought his season to an end.

Sheets made $11 million in 2008 in the final season of a four-year $38.5 million contract. He also turned down arbitration from the Brewers that would have guaranteed him a substantial raise while limiting him to a one-year contract. Based on the offseason free-agent market, it appears unlikely that he'll be able to come close to his 2008 base salary without significant incentive clauses.

Other free-agent pitchers have had to deal with similar circumstances. While CC Sabathia, A.J. Burnett, Derek Lowe and Ryan Dempster were indeed able to command multiyear deals at substantial dollars commiserate with their recent performances, others have had to rely on one-year incentive-laden contracts.

Andy Pettitte, after making $16 million each of the past two seasons, turned down $10.5 million from the Yankees, then settled for $5.5 million in base salary. He can earn another $6.5 million in incentives based on both innings pitched and time on the 25-man active roster. The gamble was taking less base to make more through incentives.

"I think time will tell," Pettitte's agent, Randy Hendricks, said at the time of the signing. "If in fact Andy does in 2009 what he's done before, he'll actually make more money, so in that case, we'll have no regrets. If things go wrong, we might be in a position to say we should have taken the left fork in the road."

Randy Johnson went from a two-year, $26 million deal with the D-backs in 2007-08 to a one-year deal with the Giants worth $8 million plus another $2.5 million in incentives based on innings pitched and games started. Johnson also gets a $1 million bonus if he wins the Cy Young Award and another $500,000 if he is traded during the season.

Mike Hampton, another pitcher with a long medical history, took $2 million in base salary and $2 million in incentives based on innings pitched from the Astros, plus $1 million for winning the Cy Young, $500,000 if he is the World Series MVP and $250,000 if he is the Comeback Player of the Year.

There are plenty of ways to bridge gaps. Troy Glaus once received $250,000 a year for his wife's equestrian training. Burnett, in his previous deal with the Blue Jays, got eight round trips per year in a limousine for his wife to go from Maryland to Toronto during the season.

Sheets' last contract with the Brewers included use of a suite for home games at Miller Park. But he also spent $50,000 per year for tickets for local children to attend games.

Contracts are rarely uncomplicated. Sheets' next deal -- whether with the Rangers or another team -- will be no exception to the rule.