The real tests come against the best offenses, when a pitcher does not have every pitch working for him and when every at-bat is a battle.
Patrick Corbin had no feel his last time out, against the Rockies. But he nevertheless held them to two runs over 6 2/3 innings as the Arizona Diamondbacks won for the fifth time in Corbin's five starts this season.
"I think I made the best of it," he said. "I wasn't as sharp as I have been, so I just wanted to keep us in the game."
The 23-year-old lefty, ranked 12th in the Majors with a 1.91 ERA, takes the hill against the Padres on Saturday. He has gone at least six innings in all five starts while allowing two runs or fewer in each. He accounts for one-third of the D-backs' 15 wins.
With a fastball averaging close to 92 mph, one tick higher than last year, and a slider he has shown more confidence in, Corbin has been a difficult pitcher to get a hold of.
Just 3.2 percent (1-for-31) of the flyballs he has allowed this year have exited the park, according to fangraphs.com. Last season, 13.5 percent (14-for-104) of his flyballs resulted in home runs.
On Saturday, Corbin will look for his first win against the Padres, who knocked him around at a .358 clip in three starts last season.
The Padres match up their own lefty in Clayton Richard, who has been uncharacteristically inconsistent around the plate, with 13 walks to 10 strikeouts in 22 2/3 innings. The Padres have lost in four of his five starts.
Richard will have the benefit of pitching against a team he is 6-0 against lifetime. The D-backs have hit .267 against him in 51 innings over eight starts.
D-backs: Putz holding on to closer job
J.J. Putz allowed just four homers in 54 1/3 innings last season, going 32-for-37 in save situations.
He has already allowed three long balls in 2013, going 5-for-9 in save opportunities. But manager Kirk Gibson said he was sticking with his proven closer for now.
"J.J. is my closer," Gibson said. "I'm going to make sure that I monitor him and give him a chance to build back up and get into the season. He's 36 years old. That's just the way he is. I want to give him a better chance to be successful. I don't want to push him as hard as I did."
On days Putz is unavailable, Gibson said David Hernandez or Heath Bell could get save opportunities.
Padres: Quentin has balky knee
Carlos Quentin was a late scratch from Friday's lineup with what manager Bud Black called a balky right knee, the same one that was surgically repaired twice last year.
Quentin had been dealing with setbacks earlier this season. He has played in just 18 games this year, also serving a suspension for his involvement with an on-field fight with Zack Greinke.
• D-backs shortstop Didi Gregorius will most likely come off the seven-day disabled list Saturday after passing medical tests following a concussion. Outfielder Alfredo Marte could be sent down to make room.
• Cory Luebke, making his way back from Tommy John surgery, will stop throwing after experiencing pain in his elbow while playing catch off a mound Monday.
• Jedd Gyorko has quietly started to heat up the plate. He went 3-for-4 Friday with two doubles. He has multiple hits in three of his seven games, when he has raised his average from .237 to .260.