DENVER -- The Dodgers have been a middle-of-the-pack defensive team in the National League, with nine more errors and a five-point-lower fielding percentage than the league-leading Phillies, but they've been good enough to build a fundamental foundation around solid fielding.

"It's one of the things we've kind of tried to hang our hat on," manager Don Mattingly said Saturday. "It's one of the things you control."

In Friday's 13-3 loss to the Rockies, however, the club committed a season-high four errors, dropping it down a couple pegs in the team fielding rankings. While a couple of the errors were the kind you expect in a game of imperfections, the mental lapses were more frustrating, resulting in Rockies getting extra bases that led to runs in prolonged innings.

"There's going to be physical mistakes," Mattingly said. "We're going to make physical errors. But those games are frustrating when you don't play good defense. I feel like we're trying to build around pitching and defense, and you can do that every day."

Mattingly has had his hands full managing a roster riddled with injuries, and the flux in the field accounts for some of the defensive lapses.

A game such as Friday night, when sloppiness in the field and a lack of timely hitting resulted in the biggest loss of the season, highlighted how much Mattingly misses one of the team's cornerstones.

"I miss Mark Ellis," Mattingly said of his second baseman who went on the disabled list with a leg injury May 19 and may miss close to two months. "He's one of those guys you don't think about and don't talk about, but you miss that guy that sits in that two-hole, makes all the plays at second base, and is just like another solid guy in your lineup.

"I thought right away, he's going to be tough to replace. Matt [Kemp] is obviously a given -- you miss Matt, that's huge production. But when a guy like Mark goes out I don't think people really realize what you're losing."

Castellanos showing Dodgers what he's got

DENVER -- For a guy who thought it was "awesome" to be hit in the elbow during his first big league at-bat Thursday, Alex Castellanos was in overdrive after his first start Friday night in Colorado.

He struck out the first time up against Rockies spot starter Josh Outman, but the next trip to the plate he tripled to right field, knocking in the Dodgers' first run and recording his first big league hit and RBI.

"First pitch he threw me a fastball inside, painted it," Castellanos said Saturday. "I wasn't looking in, I was looking away and telling myself to drive the ball the other way, and I ended up getting a pitch to do so.

"I was thinking double, and then I saw it hit the wall, and I'm like, 'I'm going three.' Test my hamstring a little bit."

Castellanos was called up Thursday to take Matt Kemp's spot on the roster, and he brought a hot bat with him from Triple-A Albuquerque. He was hitting .379 with 10 doubles, four triples, five home runs, and 14 RBIs in 22 games with the Isotopes.

"We heard a lot of good things last year when we got him from St. Louis about what he was doing in Double-A and stuff like that, and just the way he played," manager Don Mattingly said. "We really didn't get a chance to see it until Spring Training. He's a high-energy guy. He's a strong kid. He's got a good look in his eye like he loves to play. You can just see it."

With outfielder Juan Rivera's return from the disabled list set to come either Sunday in Colorado or Monday in Philadelphia, the Dodgers will likely send an outfielder down, with the probable prospects either Castellanos or Scott Van Slyke, but Castellanos is making the most of his time here, and making the case to prolong it, knocking in the Dodgers' second run on Friday with a sixth-inning sacrifice fly and singling in the eighth as part of a rally setting up the Dodgers third and final run.

"He's been impressive," Mattingly said. "He had a good spring. He swung the bat good there. He works hard. He's in great shape. He's one of those guys you like. He's been impressive, to be honest with you. There's no real negatives about Alex, at this point at least."

Mattingly not going through withdrawal over skid

DENVER -- The Dodgers started the second game of the three-game set in Colorado under cloudy skies, but despite carrying a five-game losing streak into the tilt, the club still sports the best record in baseball and a four-game lead over the Giants.

"When we were playing really well, I wasn't one that was getting too excited about it, knowing that there's storms coming and there's a long way to go," manager Don Mattingly said. "We try to get our guys thinking like that."

Whether the team was as good as it played at the peak of its spring success, the winning baseball was an investment that is paying dividends two months into the season.

"It's nice to know that we've put a little money in the bank for that rainy day," Mattingly said. "Right now, we're having to spend some of our savings. We're spending a little bit right now, but we're going to get back on track."

The rash of injuries that has spread across the roster has created a challenge for Mattingly as he fills out the lineup card each day, and there has been a fair amount of flux that is beyond his control, but he's remained a steadying influence in the dugout and he has resisted any urge to panic.

"We know there's going to be periods of time where things aren't going our way and we're going to hit a tough stretch," Mattingly said. "That's not when you start changing everything. Stay with your plans, stay with what you've done. Keep getting ready to play. And really just keep believing in what we do and what we're trying to get done."