INDIANAPOLIS -- NFL sacks champion Robert Mathis made one thing clear Wednesday: He's coming back this season as a motivated man.
In his first public comments since learning he would sit out the season's first four games for violating the league's performance-enhancing substance policy, Mathis was his usually blunt self after speaking to his Colts teammates.
"I told them I'm sorry, and I'll be back," Mathis said.
Last week, he explained in a statement that the substance, Clomid, was found in a fertility medication he was temporarily using. His wife is now pregnant.
But Clomid also can be used as a masking agent for other PED treatments, and Mathis acknowledged that the mistake he made was not checking with the NFL or the NFL Players Association to determine if the medicine could cause a positive drug test.
Some contend the explanation for making such a big jump in sacks, from eight in 2012 to a league-high 19½ at age 32, can be linked to PEDs. Mathis denied any such connection in a statement late last week and his agent, Hadley Englehard, has repeatedly said Mathis' position change, from defensive end to outside linebacker, was the primary reason his numbers improved. Mathis first made the switch in 2012 and looked much more comfortable at his new position in 2013.
He reiterated that position Wednesday.
"Let them say what they may," Mathis said. "In my heart of hearts, I know what it is and what it is not."
Under league rules, the Pro Bowl linebacker will be allowed to participate in all offseason team activities, training camp and the preseason. He will be suspended without pay for the first four games and is not eligible to return to the Colts until Sept. 29.
Mathis did attempt to appeal the ruling, but Commissioner Roger Goodell did not show any leniency.
"It's been a long process. It ran its course and I accept its responsibility," Mathis said. "I was just following directions. I shouldn't have did it. It was banned."
Teammates, like defensive end Cory Redding and Andrew Luck, accepted Mathis' explanation.
"I didn't need to hear it because I know who he is, you know?" Redding said. "I have no doubt the kind of person, the kind of character, the kind of man he is. So I didn't need to hear it for my betterment."
Losing Mathis could be a huge blow for the Colts. He is the franchise's career sacks leader and last year set a single-season franchise record. The rest of the Colts combined for 22½ sacks.
Indy does have options.
Bjoern Werner was the Colts' first-round draft pick in 2013. Though he made the same position switch as Mathis and contended with knee and ankle injuries throughout his rookie season, Werner appeared to be making solid progress over the final month.
The Colts also have outside linebacker Erik Walden, who they signed as an unrestricted free agent in 2013, and they selected college defensive end Jonathan Newsome in the fifth round of this year's draft -- a player former Colts general manager Bill Polian compared to Mathis. Polian drafted Mathis.
Redding is convinced there's enough talent to make up for Mathis' absence.
"We have 53 men on the team, probably more than that because we're going to have walk-on guys and all that kind of stuff," Mathis said. "I'm pretty sure Robert has a backup. If he were to get hurt, sprain an ankle, bust a shoelace, next man has got to get in there, right? Next man has got to get in there and play ball, period."
It just won't be easy for the Colts or Mathis.
"From my understanding, it's all set in stone, so there's really nothing you can say about it that's going to change anything," Luck said. "I know we're not wasting our breath talking about it too much. We realize the circumstance. We realize we're going to be without our best player probably for the first four games, so guys are going to have to step up."