In the nearly 17 months since then-Oakland Athletics pitcher Brandon McCarthy was struck in the head by a line drive and suffered life-threatening brain injuries, Major League Baseball says it has received and tested numerous prototypes from different vendors for padded caps to provide some head protection against high-speed shots off the bat.
On Tuesday morning, MLB informed its 30 teams that it has approved such a product for the first time, after consultation with the players' association, according to Dan Halem, MLB executive vice president for labor relations.
"We're excited to have a product that meets our safety criteria," Halem told "Outside the Lines," adding that baseball will continue its efforts to come up with more options. "MLB is committed to working with manufacturers to develop products that offer maximum protection to our players, and we're not stopping at all."
Halem and MLB senior counsel for labor relations Patrick Houlihan said the threshold for approval was that the cap had to provide protection, at 83 miles per hour, below the National Operating Committee on Standards for Athletic Equipment standard severity index of 1,200. Severity indexes higher than 1,200 are considered high-risk for skull fractures and traumatic brain injuries. An MLB-commissioned study determined that 83 mph was the average speed of a line drive when it reaches the area of the pitching mound.
The newly approved caps, manufactured by 4Licensing Corporation subsidiary isoBlox, will be made available to pitchers for spring training next month. Their use is optional.
The company says the caps are a little more than a half-inch thicker in the front and an inch thicker on the sides -- near the temples -- than standard caps, and afford protection for frontal impact locations against line drives of up to 90 mph and for side impact locations at up to 85 mph. The soft padding, isoBlox says, is made of "plastic injection molded polymers combined with a foam substrate" and is designed to diffuse energy upon impact through a combination of dispersion and absorption techniques.
"What we've given [pitchers] is a product with protection they've never had before," said 4Licensing chief executive officer Bruce Foster. "It changes the game for them."
In addition to the added thickness, the padding adds seven ounces to the weight of a cap, which currently weighs three to four ounces, said Foster. The padding is to be sent to New Era to sew into MLB's official custom-fitted caps.
"I think players who've been hit by ferocious comebackers will probably be early adopters," Foster said. The new cap, he said, won't interfere with a pitcher's comfort or motion.
"Outside the Lines" research has found that 12 pitchers have been hit in the head by line drives in the past six seasons, including five pitchers during a five-month stretch of action in 2012 and 2013. Among them was Toronto Blue Jays lefty J.A. Happ, who suffered a fractured skull and also sprained knee ligaments on his fall after he was struck in the left ear on May 7, 2013.
Asked by "Outside the Lines" whether he'd be receptive to using the new cap, Happ said he wasn't familiar with it and "I'd have to see what the differences in feel would be -- does it feel close enough to a regular cap? You don't want to be out there thinking about it and have it take away from your focus on what you're doing."
"The technology is there," he told ESPN.com. "It helps. It's proven to help. But I don't think it's ready yet as a major league-ready product. And I told them that. I told them that's where it's at."
Other pitchers reacted to Tuesday's decision by MLB.
"I think it'd take a lot of getting used to. You don't look very cool, I'll be honest."
Added closer Grant Balfour: "I am always appreciative of anything that will make the game safer. That being said, I may try it. Just not sure yet until I see it. Has to fit with a cap and be comfortable."
Four of the five pitchers who were hit in the head since September 2012, including those most seriously injured -- McCarthy, Happ and the Tampa Bay Rays' Alex Cobb -- were struck below the cap line. MLB, however, hasn't contemplated exploring protective headgear for pitchers with broader coverage, such as a visor, mask or helmet, said Halem. "There would have to be widespread willingness among players to use such a device."
But helmets could offer increased protection for pitchers, who have about one-third of a second to react to liners. Greg Rybarczyk, creator of the ESPN Home Run Tracker, said the speeds of line drives that strike pitchers can exceed 100 miles per hour, and an example he analyzed was a 107-108 mph Vladimir Guerrero line drive in 2006 that struck Rafael Soriano, who suffered a concussion.
"Short of wearing a helmet, I am doubtful there'll be a product to protect against 100 miles per hour," Halem said. "Hopefully there will be."
There is no rule limiting players as to the protection they can choose to wear, even without an MLB license, as long as what's worn doesn't interfere with play. Foster said the new isoBlox product provides some protection against speeds above 90 mph, but not protection at the same level as below that speed.
As they begin to offer the new product to major league pitchers -- whose acceptance of changes in appearance and feel is an open question -- both Halem and Foster said they see great potential for youth league players and their parents to embrace increased protection and evolving devices. Soon to hit the market, Foster said, is an isoBlox skull cap with the type of padding major leaguers will have at their disposal, except it will slide into standard adjustable caps and be removable.
"The major league market is never going to be a big market, as not that many pitchers reach the majors and a limited number will use the caps," Halem said. "But the youth market is huge."
Information from ESPN.com's Jayson Stark is included in this report.