It is early, and so there is a danger in drawing sweeping conclusions about the return on investment of any deals from this past offseason. That said, on Thursday the Red Sox offered further reminders of why costly free agent signings are such a suspect way to build a bullpen.

Both Bobby Jenks and Dan Wheeler punctuated challenging debuts with the Red Sox by landing on the disabled list prior to Thursday’s game. In some way, that outcome seemed merciful, given the way that both have struggled through their first five weeks in Boston.

Jenks, who passed on offers to close elsewhere in order to sign a two-year, $12 million deal to set up for Boston, has gotten hammered at a .333 clip, and he’s walking more than a batter an inning en route to a 9.35 ERA.

However, the Sox remain adamant he will be an important part of their late-innings management. Despite his poor numbers, Jenks had shown both velocity on his fastball (touching as high as 97 mph) and life on his breaking stuff before he encountered cramping in his arm while trying to warm up on Wednesday night.

Manager Terry Francona insisted earlier in the week that he would not shy from Jenks in high leverage situations.

“We need him to pitch those situations. For us to be the type of team we want to be, he needs to pitch in those situations,” the manager said. “For us to get where we want, we need him to get on a roll.”

That time will now have to wait.

Wheeler, meanwhile, came to the Sox on a one-year, $3 million deal as a pitcher whose deception made him an extremely tough matchup for right-handed hitters. While his limited velocity meant that he was prone to the longball, he has been a consistent strike thrower who limits baserunners (0.975 WHIP from 2008-10 with the Rays) and remains healthy.

Until Thursday, in fact, Wheeler had never been on the disabled list. But the Sox ended up placing him there due to what they are describing as a calf injury. However, it is Wheeler’s results more than his health that has raised eyebrows: He has an 11.32 ERA, and after giving up a two-run homer to right-hander Vernon Wells in Wednesday night’s extra-innings affair, he has allowed four homers in just 10 1/3 innings this year.

It is far too early to declare either pitcher a bust. Relievers are in a distinctly volatile line of work, where performances can fluctuate dramatically from week to week and month to month. But that, of course, is part of the point when it comes to the inherent dangers of signing relievers as free agents.

More than for any other position, track records may end up meaning little for relievers. Pitchers who have been successful for years suddenly reach a point where the clock strikes midnight and they turn into pumpkins. That can be especially true for free-agent middle relievers, whose effectiveness with their previous clubs leads to heavy workloads that can result in their being cooked by the time they reach a new club.

At the same time, because the margin for success as a reliever can be so small, it is an undertaking in which a relatively unheralded pitcher can become a revelation. The Red Sox are aware of that as well, of course, and have their own case study in the form of Matt Albers.

Albers was non-tendered by the Orioles in December, but he’d pitched well in the second half for Baltimore, showing improved strikeout and walk rates while getting plenty of grounders on the strength of his heavy two-seam fastball. Even so, he’s been a somewhat unexpected revelation for the Sox in the early stages of 2011.

His average fastball velocity this year, according to fangraphs.com, has been 93.6 mph, harder than he’s ever thrown in the past. He’s regularly shown 94-96 mph gas, and is throwing harder on a more consistent basis than in his career to date (although when the Sox scouted him with the Orioles, he was working at 92-95 mph and he had touched 96 mph in the past). He’s also turned more to a slider (instead of a curve) as him primary secondary pitch, and it’s been a sharp pitch in which he has gained confidence.

He has only appeared in seven games, so it would be premature to get carried to get carried away with his results. Even so, Albers has a 0.93 ERA, has shown a reliable ability to get groundballs and his pitch efficiency has made him a primary option for Francona when he needs multi-inning outings.

“He’s pitched in some higher-leverage situations than maybe we anticipated early, and he deserves it. He’s getting outs. We can’t get too much of that,” said Francona. “He’s been a blessing for us.”

Right now, the Red Sox bullpen ranks among the worst in the majors. The team has a 5.30 mark in relief, which ranks 29th among the 30 major league teams. The chief culprits have been the most expensive signings, and the reprieve has been offered by a pitcher who was not guaranteed a roster spot when he inked a one-year, $875,000 deal this offseason.

Again, that is not to say that the Sox made a mistake in their free-agent signings. There’s plenty of time for Wheeler and Jenks to turn around their seasons and to become meaningful contributors.

That said, it would be a mistake to state simply that the early returns have been less than expected, since the nature of big-money relief signings is that you simply don’t know what you’re getting for the money, a notion as true of the rest of major league baseball as it is of the Sox.

There were 17 different relievers this offseason who signed deals of at least $3 million per year with a new club. Of those, more than half have had poor showings to date -- most notably including Joaquin Benoit, who is fast becoming the poster child for reliever volatility.

Benoit was a minor league free agent who emerged as arguably the most dominant reliever in the majors for the Rays last year. After not pitching in 2009 while recovering from Tommy John surgery, he had Nintendo numbers in 2010: a 1.34 ERA, 11.2 strikeouts per nine innings and just 1.6 walks per nine innings as a Tampa Bay setup man.

After making peanuts last year, Benoit signed a three-year, $16.5 million deal with the Tigers in the first couple weeks of free agency this offseason. That length and $5.5 million average annual value of that deal served as a benchmark for everything that followed during a winter that had many baseball executives rankled over the excessive deals being given to unpredictable commodities.

In the last week, he suffered a pair of horrific losses, and he’s been unable to command his signature changeup consistently. As a result, he has an 8.08 ERA, and one year after he was the symbol of the potential to find relief diamonds in the rough, he has offered (to this point -- and it is worth repeating that it is too early to draw sweeping conclusions about the value of any deal signed this past offseason) a cautionary tale about investing heavily in relievers.

That is a reality with which the Sox are living at this early stage of the 2011 season as well.

RISKY BUSINESS

A look at the early performance of the 17 relievers who signed deals for at least $3 million per year this offseason

Grant Balfour (Athletics: 2 yrs., $8.1M): 14 games, 2.08 ERA, 11.1 K/9, 6.9 BB/9

Balfour has had good results, though his diminished control is something of a red flag.

Joaquin Benoit (Tigers: 3 yrs., $16.5M): 13 games, 8.08 ERA, 5.7 K/9, 3.3 BB/9

The man whose contract set in motion a chaotic offseason market for middle relievers has already given up more earned runs (10) in 11 innings in 2011 than he did in more than 60 innings (9) last year.

Jesse Crain (White Sox: 3 yrs., $13M): 13 games, 1.17 ERA, 11.2 K/9, 3.5 BB/9

He’s been better than advertised thus far for the White Sox, with his strikeout rate being almost double his career rate of 6.4.

Octavio Dotel (Blue Jays: 1 yr., $3.5M): 9 games, 4.50 ERA, 10.1 K/9, 7.9 BB/9

Pitchers who walk nearly a batter an inning do not get used in meaningful situations. Dotel has been little different thus far.

Scott Downs (Angels: 3 yrs., $15M): 5 games, 0.00 ERA, 3.0 K/9, 3.0 BB/9

He’s been fine when on the mound, but he’s already been on the disabled list twice -- once for a broken big toe, and a second time for a stomach virus.

Kyle Farnsworth (Rays: 1 yr., $3.5M): 13 games, 0.87 ERA, 4.4 K/9, 0.0 BB/9

The next bargain bullpen revelation by the Rays?

Pedro Feliciano (Yankees: 2 yrs., $8M): Has not played

Feliciano led the majors in appearances each of the last three years, but he was diagnosed with a torn capsule in his left shoulder in spring training, and he may require season-ending surgery.

Brian Fuentes (Athletics: 2 yrs., $10.5M): 15 games, 5.28 ERA, 7.0 K/9, 4.1 BB/9

His walk rate is higher than ever, his strikeout rate is lower than ever, and he’s already had some bad blown saves for Oakland.

Kevin Gregg (Orioles: 2 yrs., $10M): 11 games, 2.45 ERA, 8.2 K/9, 5.7 BB/9

His WHIP is, as usual, terrible, and his walks total remains a concern, but Gregg has once again been effective in save opportunities, saving six of seven.

Matt Guerrier (Dodgers: 3 yrs., $12M): 14 games, 3.86 ERA, 6.1 K/9, 3.3 BB/9

He’s had two really bad outings but been otherwise nearly perfect in the rest.

Bobby Jenks (Red Sox: 2 yrs., $12M): 11 games, 9.35 ERA, 10.4 K/9, 9.3 BB/9

He’s dealing with ineffectiveness as well as injury. The Sox still believe in the stuff, but he hasn’t been able to command thus far.

J.J. Putz (Diamondbacks: 2 yrs., $10M): 11 games, 3.00 ERA, 8.3 K/9, 2.3 BB/9

The big right-hander has been solid in his role as the Diamondbacks closer.

Jon Rauch (Blue Jays: 1 yr., $3.75M): 12 games, 4.09 ERA, 5.7 K/9, 3.3 BB/9

He’d been effective as the Toronto closer until giving up a walkoff homer to the Rays three nights ago.

Arthur Rhodes (Rangers: 1 yr., $4.10M): 9 games, 3.24 ERA, 5.4 K/9, 4.3 BB/9

He’s been adequate thus far, but the 41-year-old has seen his strikeout rate drop steeply.

Rafael Soriano (Yankees: 3 yrs., $35M): 13 games, 6.57 ERA, 5.8 K/9, 6.6 BB/9

The transition from closing to setup has not been smooth for Soriano, who has nearly as many walks this year (9) as he did in roughly five times as many innings in 2010 with the Rays (14)

Hisanori Takahashi (Angels: 2 yrs., $8M): 15 games, 6.59 ERA, 6.6 K/9, 4.6 BB/9

The left-hander was last seen serving batting practice at Fenway Park. He’s given up four homers in 13 2/3 innings.

Dan Wheeler (Red Sox: 1 yr., $3M): 11 games, 11.32 ERA, 7.0 K/9, 0.9 BB/9

Wheeler has generated a respectable strikeout total, but opponents are hitting .375 with a 1.075 OPS against him. He’s allowed four homers thus far this year, and is now on the DL with what the Sox have described as a calf strain.