CLEARWATER, Fla. - The route that Darin Ruf used to navigate leftfield in the top of the third inning on Thursday looked a lot like the route a paper airplane might have taken had it been thrown in the general direction of Ramiro Pena's sinking line drive.

Turns out, the shortest distance from point A to point B is not a converted first baseman. That doesn't qualify as a revelation, of course. At no point over the last 3 months have the Phillies given the impression that they envision Ruf as their Opening Day leftfielder. Charlie Manuel has a soft spot for the guy, as does anybody who witnessed him slug 41 homers between Double A and the majors last season.

But after watching Ruf scramble back to the wall to retrieve the ball as Pena rounded second and headed toward third, it was impossible to maintain much hope that the Phillies' biggest project would start the season as their leftfielder.

Do not mistake any of this for an indictment of the player. Ruf is a first baseman who is trying to play the outfield, and what we have seen thus far is what one would expect to see from somebody who has been trying to do so since only last July. Problem is, Manuel can trace those kinds of defensive lapses to no less than five of the Phillies' 81 losses last season, at least two of them against the Braves.

You remember those moments, don't you? Moments like the ninth inning of a Sept. 2 game at Turner Field, when Kevin Frandsen, playing third, botched what should have been a game-ending groundout to set up a three-run walkoff home run by Chipper Jones. Like May 2, when the Braves entered the eighth inning down four but took a 13-12 lead on a fielding error by shortstop Jimmy Rollins. The Braves went on to win in extras on another walkoff by Jones. Both of those losses almost surely would have been wins without the errors.

Look back over the Phillies' schedule and you'll find a commonality shared by most of the errors that led to game-changing unearned runs: They involve a player who was not the optimal defensive solution at his position. On April 8, Ty Wigginton botched a throw from catcher Brian Schneider on a swinging strikeout that led to two unearned runs in a game the Phillies would lose 5-4. In August, Frandsen unleashed an errant, eighth-inning throw with the Phillies up 4-3 in Milwaukee. Instead of the inning being over, Josh Lindblom replaced Cliff Lee and gave up a grand slam to Corey Hart. There was the June game when a 10th-inning error by Wigginton, playing third, led to an unearned run in a 5-4 loss to the Orioles.

Asked how big of a role defense will play in the Phillies' decision-making process, Manuel didn't hesitate.

"Very big," he said. "Fundamentally, we have to play better. We have to play defense in the big moment."

The Phillies would have plenty of questions about their defense even if they found a proven Gold Glover to play leftfield. At 36, Michael Young is trying to play third base regularly for the first time since 2010. Rightfield could feature Domonic Brown or, when healthy, Delmon Young, neither of whom are known for their glove work. Carlos Ruiz will be missing from behind the plate for the first 25 games for a violation of the league's drug policy. The Phillies plan on keeping Freddy Galvis on their bench because of his ability to play third base, second base or shortstop in late-and-close situations. They selected Ender Inciarte in the Rule 5 draft because of his glove in centerfield.

"Defense is very important to us," Manuel said. "Good defense keeps from allowing opponents four or five outs in an inning, good defense helps your pitcher go deep in a game . . . In the big leagues, you are supposed to catch and throw the ball. That's probably one of the biggest differences when you go down to the minor leagues."

Manuel was not talking about Ruf, or any player in particular. With Delmon Young expected to open the season on the disabled list, the Phillies could decide to keep Ruf on the bench as a righthanded power bat. But they could also try to hang on to Inciarte for as long as possible instead of returning him to the Diamondbacks, which they would have to do if they remove him from the active roster. With John Mayberry Jr. and Laynce Nix available to rotate in leftfield, and with Brown playing well in right so far, the best place for Ruf might be Triple A, much like Brown a couple of years ago when the Phillies sent him down to work on his defense.

"Darin is going to make some mistakes," Manuel said. "Hopefully he can keep working and we'll see how much he improves before the end of the spring."

One thing is clear: Defense will be a priority when it comes time to set the Phillies roster.

On Twitter: @HighCheese