Tulowitzki, out of the lineup Wednesday -- in the rubber game of three with the Padres -- for the first time this season, has six errors in 63 chances this season, after finishing last year with six in 684 chances en route to his second straight Gold Glove.
Tulowitzki is also hitting a sub-par .244, but the defensive errors are alarming to the Rockies, their fans and himself.
"Sometimes, I'll look back at a season and say, 'Wow, that was a good fielding season. I didn't even know I had that in me,'" Tulowitzki said. "Now that I'm off to this bad start and matched my error total, I know that stuff, but I'm also a fan of the game. I realize this happens. There are some pretty good players that this has happened to. It just hasn't happened to me yet.
"It's tough to sometimes just be out there and say, 'Is this really going on?' It doesn't seem real, but it is."
Tulowitzki's throwing, his calling card, has deserted him. Four of his errors have been on throws. He had seven throwing errors as a rookie in 2007 but no more than four in any season since. He said two explainable throwing errors -- Friday night, when he was playing in wet and cold conditions against the D-backs -- triggered some counterproductive thoughts, such as when he's playing catch and has to make perfect throws.
In the seventh inning Tuesday night, with Jamie Moyer trying to become the oldest pitcher ever to win a game, Tulowitzki let a groundball go beneath his glove and nearly blew Moyer's bid. But Tulowitzki was bothered more by a throwing error earlier in the game, when he had plenty of time.
"That goes between my legs, I'm honestly convinced that happens even if I'm not in this little funk that I'm in," Tulowitzki said. "It's just a ball that I missed. It's the throwing ones that I'm sitting there thinking about.
"I'm taking the field and thinking about it. I never thought about defense. I just go out there and play, and if I make an error, I made an error. But I wasn't worried about it. So, yeah, I think about it. It's in my head. I'd be lying if I said it wasn't in my head. I think about it because I care."
Manager Jim Tracy is not avoiding the subject, but he's not making a big deal of it.
Tracy said he went to Tulowitzki a few days ago and told him he would be rested Wednesday. The team is off Thursday before going to Milwaukee Friday to begin a three-game series and six-game road trip. Tracy said it's a matter of "not feeling like in the case of any of these guys that we're grinding on them to the point where we're running the risk of running them into the ground."
Marco Scutaro moved from second base to short, and Jonathan Herrera started at second on Wednesday.
Tulowitzki's close friend, veteran first baseman Jason Giambi, pulled him aside to watch video after Tuesday's game.
"I showed him some highlights of him playing and said, 'That's you.'" Giambi said. "I said, 'I know. I've been there many times, the deer in the highlights look and you're just reeling.' He'll get through this just great. He'll be fine.
"Tulo is the rare superhuman who can play both sides of the ball. For him, he's so good that it's tough. He has two things he's not doing very good right now. But it's OK. He's learning some valuable lessons right now.
"Sometimes, it's nice to see it. We're all human beings. He's going to come back stronger and better, and people will be amazed. I've seen this before. I don't know if it's going to be one diving play. I don't know if it's going to be one bloop hit, and it's going to be that Tulo that was in September -- 18 homers."
Tulowitzki appreciated the help from Giambi.
"During these times, you want to talk to people that care about you, because everybody's going to put in their two cents and think that something's wrong," Tulowitzki said. "He's one of those guys you consider a true friend. He cares more about the person than he does about results on the field. That helps a lot."
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.