© 2014 MLB Advanced Media, L.P. All rights reserved.

6/9/2014 10:41 P.M. ET

Walker undergoes appendectomy, placed on DL

PITTSBURGH -- Pirates second baseman Neil Walker was a late scratch from the lineup Monday due to abdominal pain.

It was later revealed that Walker needed an appendectomy and was subsequently placed on the 15-day DL. With the move, the Pirates recalled top prospect Gregory Polanco from Triple-A. Josh Harrison, who started at second base in Monday's 6-2 victory over the Cubs, will remain there as Polanco will play in right.

Walker had played in all of the Pirates' first 62 games this season and started in the first 58, being held out of the starting lineup against the Padres last Wednesday for the first time before appearing for a pinch-hit at-bat in the eighth inning.

The switch-hitting Pittsburgh native is batting .280 with 35 RBIs and 11 homers. His RBIs are tied for most on the team along with Pedro Alvarez, and Walker has the most home runs of any National League second baseman.

First-round pick Tucker agrees to terms with Bucs

PITTSBURGH -- The Pirates and first-round pick Cole Tucker have agreed to a $1.8 million signing bonus, MLB.com confirmed Monday.

Tucker, the 24th overall pick, reportedly agreed to a deal which was slightly under the pick value of $1.9255 million. As of Monday, the Pirates did not confirm the agreement.

A high school shortstop from Arizona, Tucker hit .404 with 30 RBIs in his final season at Mountain Pointe High and also played for the 18-and-under U.S. national team.

Tucker will likely begin playing professionally in the Gulf Coast League later this month.

Melancon focused on continuing to improve defense

PITTSBURGH -- The discussion with Mark Melancon involved his uncanny ability to induce and cleanly field comebackers, when the Pirates reliever posed an interesting question.

"Has a relief pitcher ever won the Gold Glove?" Melancon asked.

Told that the positional award for fielding excellence, distributed since 1957, has never gone to a reliever, Melancon said, "If a reliever is going to win a Gold Glove, I'd like to be the one to do it."

A strange wish for a reliever, perhaps. But, then, Melancon's emphasis on fielding his position is also slightly eccentric. For instance, no pitcher has ever before been heard to say, "I enjoy PFP [pitchers fielding practice]."

"Fielding is very important to me," Melancon added. "Part of my offseason work is getting into a routine to help my defense. Last winter, I got on a racquetball court, and had racquetballs fired at me off the walls, because they come back at you so quick. Helps with the reaction.

"I'm trying to get a tennis-serving machine for my wife, then use that, too, to have balls shot at me. Anything you can do on the mound to help yourself ... plus, it's also for protection."

Melancon has cleanly handled all 10 of his fielding chances. If that doesn't seem like an unusually-heavy workload, consider that, an inning at a time, he has worked only 29 innings.

Working on return, Cole throws on flat ground

PITTSBURGH -- The most encouraging activity on Monday at PNC Park took place long before the gates opened, before fans could get a lift out of what was transpiring in short center.

There, under the watchful eye of pitching coach Ray Searage, Gerrit Cole played catch. Seeing a guy normally able to fire 97-mph fastballs lob balls 60 feet may not be a big deal -- unless it's a centerpiece guy who had gone on the disabled list the day before with shoulder fatigue.

The flat-ground catch, of 25 pitches, was the first time Cole had thrown since Wednesday, when it caused him enough discomfort to loop in team brass, leading to his DL stint.

"I don't see it as a huge issue," Cole said, "just something that needs to be taken care of. It's just my body letting me know that we need to get this right. I'm looking forward to getting back in the routine.

"It's the right point of attack. Fortunately, we have guys like Jeff [Locke] who can step in."

Locke, recalled from Indianapolis to take Cole's turn in the rotation, allowed three hits and one run in seven innings in a 1-0 loss to the Brewers on Sunday. The lefty will remain in the rotation, and take Cole's next turn, Friday in Miami against the Marlins.

First number, last word

9: Times Pirates starting pitchers have allowed five-plus earned runs this season. Arizona led the Majors in that category through Sunday's games with 18.

"If it starts working out like this on six days for everybody, we'll just have to add another starter." -- Pirates manager Clint Hurdle, on Charlie Morton pitching against the Cubs on Monday with an additional day of rest, the day after Jeff Locke pitched three-hit ball for seven innings under the same circumstance.

Worth noting

• Monday night's game was the Pirates' 62nd since their only shutout of the season -- the Opening Day 1-0 victory in 10 innings over the Cubs. At 62, it would match the Bucs' longest stretch without a shutout in five years, from April 21-June 29, 2009.

• Former Pirates reliever Brad Lincoln is the reigning International League Pitcher of the Week, with Lehigh-Valley, the Phillies' affiliate.

• Entering this series with the Cubs, the Pirates had a record of 13-7 in the opening games of series, including wins in the last five.

Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. Stephen Pianovich is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.