HOUSTON -- Arizona leads the National League in numerous offensive categories, including runs, hits, homers and slugging percentage. Five of the 10 longest home runs in the NL this season have been hit by the D-backs.

This week, second baseman Kelly Johnson was named NL Player of the Month for April. Center fielder Chris Young is batting over .300, and catcher Chris Snyder and first baseman Adam LaRoche also provide power.

But the player with the most upside is 22-year-old Justin Upton.

"I'm not going out on a limb," said D-backs batting coach Jack Howell, "but I think Upton is the guy. It's not putting a lot of pressure on him. He's had that type of pressure on him from the time he was in high school, and he handles that real well.

"He's a guy I think 10, 11, 12 years from now, we'll be talking about the numbers he's put up, and he's going to be a phenomenal player."

The right fielder is already in his fourth season with the D-backs and last year, made the NL All-Star team and joined Orlando Cepeda (1959) of the San Francisco Giants as the only players in Major League history to hit at least .300 in a season with 25 homers, 80 RBIs and 19 stolen bases at age 21 or younger.

On Monday against the Astros' Roy Oswalt, Upton homered to dead center, measured at 453 feet, for the game's only run.

"He hasn't really come close to understanding who he is," said Howell. "He's talented and hard working and strong. He has balance and great presence at the plate and yet, just a puppy when it comes to a big league hitter."

Hinch remains confident in Gutierrez

HOUSTON -- Juan Gutierrez allowed Carlos Lee's two-run, walk-off homer in Wednesday's 4-2 loss to the Astros, but Arizona manager A.J. Hinch has no immediate plans of moving his reliever to the back of the line.

"Guti has good stuff and found himself in a game-deciding situation," said Hinch. "I'll keep giving him the ball, I believe in him. [Thursday], I will stay away from him.

"That's more about work load and giving him a mental break after a night like last night. We have a lot fresher arms down there."

On Wednesday, Gutierrez faced only two batters after entering in the bottom of the ninth in a 2-2 game. He walked Kazuo Matsui on five pitches and on his first pitch to Lee, the Astros left fielder belted a towering shot out over the railroad tracks atop the left-field wall at Minute Maid Park.

In 13 games, Gutierrez is 0-4 with a 7.30 ERA over 12 1/3 innings.

Ryal gets first start in left field

HOUSTON -- Arizona manager A.J. Hinch said Rusty Ryal's first start in left field on Thursday in Houston is well earned. Hinch has taken note that Ryal is ready for all his roles -- off the bench, pinch-hitter and occasional starter at first base.

The right-handed-hitting Ryal has played first base five games this season, with two starts, and has come off the bench to play left field four times. Gerardo Parra has started 15 games in left for the D-backs.

"He's been very prepared when he's gotten the opportunity," Hinch said of Ryal. "And that's not an easy role for a younger player and someone who doesn't have a ton of at-bats under his belt.

"He's a good weapon. The way he's hit off the bench late in games has been good. He's starting [Thursday] against a lefty [Wandy Rodriguez], which he's earned. Nothing against Parra or [Cole] Gillespie, it's more give him the opportunity to get the start."

For the season, Ryal is batting .400 overall and .400 as a pinch-hitter. Last season, he hit .271 (16-for-59) over 30 games.

"He has a nice, efficient swing," said Hinch. "It's pretty low maintenance in that he can come and time up anybody's fastball. He's in there for his bat."

On Sunday at Chicago, Ryal went 2-for-4 with a two-run homer, his first of the season.

In Wednesday's 4-2 loss to the Astros, Ryal had a pinch-hit single in the ninth off Astros closer Matt Lindstrom. After Wednesday's game, Hinch told Ryal he would be starting on Thursday. When he's not starting, Ryal has to be ready to come in as a late-inning replacement or pinch-hitter.

"When you come off the bench, you make sure you get plenty of work in batting practice," said Ryal. "And the games you are starting, just train your mind on what your game plan is going to be as a starter."

Reynolds wants to play every game

HOUSTON -- Arizona third baseman Mark Reynolds loves to play baseball. He loves the game so much that he never wants to come out of a game, even when he has a nagging injury.

"Reynolds is a guy you have to yank out of the lineup," said Arizona manager A.J. Hinch. "He's not going to come in and ask for a day off. He's not going to tell us the truth about how he's feeling. He wants to play every game.

"I'll do the thinking for him sometimes and make it non-negotiable. Right now, he's managing it OK."

Reynolds has been nursing a quad muscle, but he's missed only one game this season.

Arizona's last day off was April 22, and Thursday's game at Houston was the D-backs' 14th in as many days of a 20-game stretch in 20 days. The D-backs' next off-day is May 13 following a three-game home series with the Dodgers.