It was well and good to be called “a tough kid” by Terry Francona, but really, the Red Sox manager’s credentials to make that call only go so far. Recently retired Ultimate Fighting Championship star Chuck Liddell is another matter entirely.

Liddell was on hand at Fenway to watch his friend Brad Penny win his 100th career game. Yet the pitcher almost never had that chance. In the top of the first inning, Marlins outfielder Jeremy Hermida smashed a liner straight back up the middle that hit Penny on the left side of the chest.

“I guess it hit me in a pretty good spot,” said Penny. “Right over the heart.”

The ball bounced off as him as if propelled by a string, rolling directly to first baseman Kevin Youkilis who stepped on first to retire the side. Penny shrugged off the ricochet and remained in the game, firing five innings in which he allowed just one unearned run.

In the process, he earned an accolade that Liddell does not throw around lightly.

“I saw the bruise, man. (Penny) is pretty tough. That hurt. Those balls fly. It was moving pretty fast,” said the former UFC light heavyweight champ. “I’d do alright (if hit by a line drive). I’ve been hit once or twice. But he’s a tough (expletive), man.”

“You can't hurt him,” added Francona.

Yet while toughness was the most glaring element of Penny’s milestone victory, a 6-1 victory over the Marlins (recap here), it was not the most important. More significant was that he was once again delivering the baseball with tremendous power, his “explosive fastball” (in the words of Francona) crackling through the strike zone at 95-97 mph all night.

Though Penny’s curveball did not have the same devastating effect that it did in his previous start, he did complement his heater with an outstanding changeup. His command faltered on occasion, most notably when he walked three batters in the first two innings while laboring through 58 pitches.

But even that element of his outing, suggested Penny, was cause for optimism about his most impressive stretch to date.

“I feel really strong. I think that was one of my problems tonight. My command, I felt a little too good. The last two games back-to-back have been the best I’ve felt in probably five years…Velocity was back where it was when I was 21,” said Penny, referring to a two-game stretch against the Marlins and Yankees in which he has allowed one unearned run in 11 innings. “I just think the shoulder program they have got me on here when I came over…it’s incredible. I really believe if I hadn’t signed here I wouldn’t be pitching.”

But pitching Penny is. In six starts since May 20, he is 3-1 with a 3.12 ERA. For that reason, a sense that he needs to be traded to free a rotation spot for another pitcher has subsided.

With John Smoltz making his final rehab start on Wednesday, dialogue about Penny now focuses on how he can be kept in the rotation. For the short term, the Sox will employ a six-man rotation to ensure that Penny – pitching at an increasingly elite level – remains in the fray. For the longer term, Penny suggested, the Sox face a tough but ultimately good problem of a pitching surplus.

“There’s a place for everyone. If you get traded or if you’re here, I think there’s a place for you to pitch,” said Penny, who improved to 6-2 with a 4.94 ERA. “I don’t think I’ll be traded, but there’s always that chance.”

Whatever happens, Penny’s value is clearly growing by the start. He seems increasingly capable of helping the Red Sox either by what he delivers on the field or what he might fetch the club in a trade off of it.

That, and he is a very bad dude.

Here are four other things we learned as the Sox improved to 12-3 in their last 15 games:

DUSTIN PEDROIA LOOKED TO RIGHT TO FIND HIS ANSWERS

The move to the leadoff spot by Dustin Pedroia on May 30 may have coincided with one of the best stretches of the season for the Sox, but it certainly did nothing to help the offense of the Sox second baseman. In his first dozen games in the leadoff role, Pedroia hit .170 with a .267 OBP and .531 OPS, including a particularly dismal 2-for-28 (.067) jag in the six games leading up to the Marlins series.

But Pedroia showed signs of life on Tuesday, collecting a pair of hits, most notably when he ripped a ball to right field for a single. On Wednesday, he seemed to cement that progress by going 3-for-5 and driving in three.

“I hit those things, everyone does. You go through a tough time throughout the season,” said Pedroia. “You play so many games in a season, you're going to have tough bumps in the road but you get back on track.”

In this case, Pedroia seems to have done so by an approach that features him lining balls to the opposite field. He ripped singles to right in the third and fourth innings (the second coming with the bases loaded to drive in two) and then hit a hard grounder back up the middle, just to the right of second, with the bases loaded to drive in another run in the eighth.

“He’s using all of the field. When you see Pedey reaching down, hitting balls to right-field, hitting the ball up the middle, then more often than not somebody will try to come in and he’ll turn on something,” said Francona. “(Bench coach Brad Mills) actually made a comment to me. He goes, ‘I don’t think they know what to do (against Pedroia).’

“Bases loaded, if you elevate, teams used to try to do that and he gets on top of it. You throw him a ball a foot off the plate and he hits it to right. I think there’s times when Pedey’s feeling good about himself that it probably doesn’t matter (how you pitch him).”

With the bases loaded, Pedroia is now a career .432 hitter (17-for-37) with a .488 OBP and 1.110 OPS.

JACOBY ELLSBURY IS HALF-WAY TO THE BEST MONTH OF HIS CAREER

Jacoby Ellsbury wasn’t perfect on Tuesday. In the first inning, he put Penny and the Sox in an immediate hole when he failed to secure a line drive into the gap in left-center that glanced off his glove.

The development was briefly stunning. It was Ellsbury’s first career error, following a streak of 232 games and 554 chances without a miscue (the longest errorless streak ever by a Sox outfielder).

But the outfielder more than made up for it by continuing an outstanding run at the plate that is as impressive as any in his career. Ellsbury took a pair of walks, stole a base and absolutely tattooed a homer into the right-field bleachers, just beyond the intersection of the home and visiting bullpens.

The homer was Ellsbury’s second in four games, and continued a phenomenal June in which he has hit .375 with a .469 OBP, 1.019 OPS and seven steals. If the 25-year-old sustains this pace for another two weeks, this could be his best month in the majors.

His current single-month bests:

AVG - .361 (Sept. 2007)
OBP - .396 (May 2008)
OPS - .927 (Sept. 2007)
SB - 18 (May 2008)

Ellsbury’s offensive eruption has come at a time after he was removed from the leadoff spot. He initially batted lower in the Red Sox order, and has spent the past few games batting second.

“I do think (the lineup change) has helped our ballclub because we’re trying to us emore of our guys’ strengths and I think it’s worked out well,” said manager Terry Francona. “But I think wherever he’s hitting, he’s a good player.

“Now that he’s hitting, whether it’s second, seventh, he makes so many things happen. He’s swinging at strikes. I just think he’s starting to feel better about himself.”

THE BULLPEN IS BUILT TO LAST

The first bullpen group sailed through its three shutout innings on Tuesday, with Manny Delcarmen, Takashi Saito and Daniel Bard each delivering a scoreless frame. On Thursday, the Sox asked a completely different group to lock down a victory, and Justin Masterson, Hideki Okajima, Ramon Ramirez and Jonathan Papelbon each pitched a shutout inning to do just that.

In consecutive games in which the Sox got just 11 innings from their starters and needed seven from the bullpen, not a single reliever was asked to record more than three outs. The development is a testament to the shared bullpen workload that has the Sox optimistic that they can continue to dominate the late innings.

The Boston bullpen now has a collective 2.90 ERA that is far and away the best in the majors. And the team is confident that it can distribute innings across a deep and talented group to ensure that its relievers do not suffer a fall-off.

“We are certainly striving to (keep everyone fresh),” said Francona. “If you have a good bullpen and you wear them out, that’s not going to do anybody any good. You let them have their proper rest, and they have some pretty good ability out there. That’s part of what we’re trying to do.”

The 25 innings of work by Sox relievers without a day of rest rank 10th in the American League. There have been 27 occasions when the Sox have asked a reliever to pitch without any days of rest in between appearances; it has been more than a month since the Sox last asked any of their pitchers to work on three or more consecutive days, when Ramirez pitched on four straight days from May 1-4.

All of that has contributed to a group that feels strong as the season moves within a couple weeks of the halfway point.

“I’d like to think we all feel somewhat fresh,” said Justin Masterson, who delivered an overpowering inning in which he struck out two. “I’ll tell you – that’s the great thing about having so many great arms. We’ve done a great job of mixing everyone in, pick your times, trying to make sure they stay rested.

“I think we’ve done a great job thus far. The history of baseball (shows) having a strong bullpen and pitching will be one of those key processes to help you get into the playoffs and maybe farther in the playoffs.”

That is not to say that the Sox have not asked a lot of some of their relievers. Ramirez is tied for third in the A.L. with 31 appearances, while Okajima is tied for eighth with 30. But in the past 30 days, both pitchers have pitched in just 11 games, tied for 20th in the American League.

The Sox are taking as many precautions as possible to keep its relief corps intact for the long-haul. The reason for that approach is readily apparent: the team’s bullpen is an area of enormous strength that deserves nearly every precaution, particularly as the team readies for a six-man rotation.

“It’s a great bullpen. We have great arms,” said Ramirez. “I believe this is the best bullpen I’ve ever seen in my life.”

KEVIN YOUKILIS IS NOT SLUMP-PROOF

Not everything was roses in the Red Sox lineup on Wednesday. The Sox’ best hitter dug a bit deeper in what is easily his worst slump of the season, and indeed, since the 2007 season.

Kevin Youkilis went 0-for-4, striking out three times and stranding five baserunners. In four weeks since returning from the disabled list (strained oblique), Youkilis has been a different hitter than the player who terrorized pitchers over the season’s first four weeks. That has been particularly true this month, when he has been swinging and missing at an eye-opening rate.

Before landing on the disabled list, Youkilis struck out just 18 times in 109 plate appearances (1 every 6.1 trips to the plate). Since returning, he has 35 punchouts in 116 plate appearances (1 every 3.3), including three whiffs in four trips to the plate on Wednesday.

This month, though he is still reaching base frequently (.391 OBP), he has not hit for either average (.204) or power (.388 slugging).

That said, if a .779 OPS represents a noteworthy slump, then a player has set a rather extraordinary standard for his performance. Youkilis still leads the American League with a .453 OBP.