Arms are fragile. Everyone in baseball knows that. But managers become acutely aware of it when their teams embark upon a doubleheader.
That will be the case at Citi Field on Sunday, where two last-place teams, the Mets and D-backs, will wrap up a three-game series with a single-admission doubleheader after Friday's opener was postponed in the fourth inning due to rain.
Quality starts will certainly help, which is why Mets manager Terry Collins likely allowed Zack Wheeler to throw a career-high 118 pitches over 6 2/3 innings on Saturday. Even without using his bullpen Friday night, Collins used four relievers -- Josh Edgin, Carlos Torres, Scott Rice and Jose Valverde -- to spell Wheeler. Currently, the Mets are in the midst of playing four games in the span of 48 hours, part of a string of 20 games in a row that started against the Dodgers on Tuesday.
Arizona, meanwhile, will have a quick turnaround after Sunday's doubleheader, flying back to Phoenix for a Monday night game against the Padres.
Rafael Montero, still battling for a spot in the rotation with fellow rookie Jacob deGrom, will make his third start of the year in Game 1 for the Mets. The young righty has lost both of his outings at Citi Field thus far, allowing eight earned runs over 10 1/3 innings as he helps fill in for an injured Dillon Gee. Arizona will counter with Bronson Arroyo, who has posted a 4-3 record and 4.45 ERA in nine starts.
Even with his own club hard-pressed to save its bullpen, which pitched three innings on Saturday, Arroyo doesn't believe in changing his approach.
"You prepare to go nine innings every night," Arroyo said. "You're going to go out with the same mentality, but if you start to get beat around, you're going to have dig your heels in a little bit. [I] realize I might have to wear it a little bit, even if you don't have your best stuff, just based on the best interest of the whole ballclub."
The matchup in the nightcap will feature pitchers who haven't made a start this season. The Mets will throw Daisuke Matsuzaka to the hill, knowing his past capabilities of going deep into games. In 14 appearances as a reliever, Matsuzaka has allowed just five earned runs in 21 innings, but doesn't expect this to be an audition for a starting spot.
"I don't see it being anything long term, it's probably just for Sunday," said Matsuzaka, who started seven games last year for the Mets. "I have a responsibility as a starter to pitch deep in the game and that's what I expect to do."
Meanwhile, an audition for a starting spot might be the best way to describe right-hander Zeke Spruill's situation, considering D-backs starters have allowed a league-high 5.2 runs per game. According to manager Kirk Gibson, the 24-year-old, who in six games and two starts last year allowed opponents to hit .354 in just over 11 innings, will join the team as the 26th man on the roster.
"All things considered, he's thrown the ball the best," said Gibson. "He's been here before, he had some starts for us last year. I hoped that was the right way to go and so I'm looking forward to him throwing a good game for us.
"He's got very good stuff: good arm, ball moves. He doesn't seem to be severely fazed by pressure. He's pitched in Reno where they had a humidor but it broke. So he understands the importance in keeping the ball down."
Mets: Black briefly joins the bullpen
Like the D-backs did with Spruill, the Mets will add hard-throwing reliever Vic Black to fill their 26th roster spot for Sunday's doubleheader. The righty was recently clocked throwing his fastball at 98-99 mph, but is still struggling with command issues.
For Triple-A Las Vegas, Black has recorded seven saves and posted a 1.45 ERA in 17 appearances. However, more batters have reached via walk (18) than base hit (12) in Black's 18 2/3 innings.
"He has not been getting hit, but the command is just not what we would like it to be for a guy you project to be the closer one day," said Collins. "So if we can get him to have better command of his stuff, he'll never see the Minor Leagues again because his stuff is plus."
Collins, who did not rule out the possibility of Black staying in the Majors beyond Sunday, raved about the reliever's arsenal of pitches. Last year, when he pitched in 18 Major League games for the Pirates and Mets, Black relied mostly on a fastball that averaged 96 mph and a curveball that dipped into the low 80s.
"It's all there," Collins said. "He's just got to get it in the zone."
D-backs: An emphasis on defense
The D-backs, in their quest to improve, are putting an emphasis on defense, said first baseman Paul Goldschmidt. Arizona's fielding percentage this season is .980, which is the one of the lowest in the Major Leagues.
Goldschmidt, much like many of his teammates, knows he can do better. Through 50 games, Goldschmidt has almost as many errors this season (four) as he had all of last season (five) in 159 games.
"There's been some positives, but I think there's been some mistakes I've made," Goldschmidt said. "You're working on it daily. It might not even be an error. Maybe you throw to a different base or your positioning was a little bit off."
As a team, the D-backs have 37 errors, which ranks fifth in the Major Leagues. The Reds, who lead the Majors in the fielding percentage, have less than half that many errors (19) in comparison.
"I know we haven't played up to our potential," Goldschmidt said. "We haven't done as good of a job as we need to do. For us to not be playing well this stage of the season has really taken everything -- and defense is a part of it."
• Martin Prado has hit safely in seven of his last 10 games against the Mets, which included a two-hit, two-RBI performance on Saturday.
• Collins mentioned before Saturday's game that closer Jenrry Mejia might be used in both games of Sunday's doubleheader, since he didn't pitch Saturday. "I'd have to be very careful," Collins said.
Jake Kring-Schreifels is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.