Thomas said it boiled down to something else entirely:
''Letting down Peyton.''
That's the thought that invaded his mind when he was running free with two blockers in front of him against Indianapolis and Manning's pass inexplicably skipped off Thomas' hands.
Unable to forget it and move on, one drop turned into another. And another. And so on.
Thomas, who piled up 217 catches for 3,117 yards and 28 touchdowns, counting playoffs, the last two years, was mired in the first bona fide slump of his five-year NFL career.
Heading into the bye week last month with just one TD catch to go with four drops, Thomas consulted Hall of Famer Shannon Sharpe and Broncos Ring of Famer Rod Smith, both of whom told him he needed to clear his head.
When he returned from the bye last week, Thomas went out onto the practice field on his own time and caught 250 passes on Monday, then put in extra work the rest of the week, one of the reasons his position coach, Tyke Tolbert, declared his slump over.
''All the chips are in on us seeing the old Demaryius,'' Tolbert said last week. ''Everybody at some point in time will go through some type of slump. And he's through his slump. Luckily for him, he got it out of the way early. So, I look forward to nothing but great things from Demaryius this Sunday through the rest of the season.''
Asked why he would declare Thomas' slump over before his star even had a chance to prove it in a game, Tolbert said: ''I think his approach and the fact that all our guys are back now. We missed Wes the first couple weeks of the season. We shuffled guys around but everybody's back doing stuff they've always done, so I see everybody has a more stable mindset right now. I see the improvement in practice. And I expect nothing more than to see it in the game.''
Tolbert's words proved prophetic. Thomas caught eight passes for a franchise-record 226 yards and two long touchdowns in Denver's 41-20 rout of Arizona on Sunday when Manning threw for a career-best 479 yards.
Manning saw the signs of a breakout, too.
''Demaryius challenged himself during the bye week,'' Manning said. ''He knew he wasn't playing up to his capabilities. He has high goals and high standards and for whatever reason, I think he's been thinking a lot. We did put him in the slot early with Wes out. He's been thinking a lot and it's just affected his concentration with catching the football.
''I think he just had a good look in his eye all week and he got back to his fundamentals.''
Thomas' big day included touchdown catches of 31 and 86 yards. Were it not for a chop block penalty negating his 77-yard TD catch, Thomas would have posted just the sixth 300-yard receiving day in NFL history.
''It's all right,'' Thomas said. ''Everybody makes mistakes. We got back out there and were able to put up more points and to get a win, and that's really all that matters.''
The usually sure-handed Thomas, who even made the erratic Tim Tebow look good back in 2011, had a trio of drops against Indianapolis on Sept. 7. All came within 4 yards of the line of scrimmage with significant yards after the catch a possibility.
''I had to play slot because Welker was out and I'm not used to that,'' Thomas said. ''I knew if it was like third-and-5, Peyton always went to Welker and I knew if I'm not open, he's going to be on me. So I was thinking when I got the ball coming my way, I would drop it, and first one I dropped. I let it get to my head: `I'm letting down Peyton, I'm letting down my team.'''
So, breaking out of his funk, he said, was a matter of ''just being back in my position and being more comfortable.''
With an unclouded head and a clear conscience.
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