Cole Hamels is used to all the attention - from Phillies fans.

But every fifth game this season, continuing likely for the next three-plus months, the Phillies ace will take the mound with eyes on him from all over Major League Baseball.

For five of his spring training starts, scouts squeezed into the seventh and eighth rows of Section 111 at Bright House Field in Clearwater, Fla. For the other, they watched at Florida Auto Exchange Stadium in Dunedin. This will be customary in big-league ballparks throughout April, May, June and July, or as long as the rebuilding Phillies hold on to their ace.

The Phillies' handling of Hamels, by far their biggest trade chip, should be telling in the progress of the team's rebuilding. While still in his prime and under contract for the next four seasons, the talented lefthander would bring back a return that could expedite the transition.

For that very reason, general manager Ruben Amaro Jr. will likely hold out until the days leading to the annual July 31 non-waiver trade deadline to try to maximize a potential return. At that point in the season, a team eyeing the postseason might be more willing to part with the prospect package the Phillies seek in exchange for Hamels.

Until then, the constant trade speculation will persist.

"We listen on any of our players, and if it was the right situation and we thought that it would speed things up for us, I think Ruben would go ahead and do it," Phillies president Pat Gillick said in an interview during spring training. "But I don't think, really, on any of our players, including Cole, I don't think there's been a deal there where we said, 'Hey, let's go do that one. Let's do it.' "

At 31, Hamels is still young enough that he could theoretically headline the next Phillies core. He is entering the third of the six guaranteed seasons on the contract extension he signed in July 2012. His deal calls for $23.5 million in base salary in each of the next four seasons and a $20 million team option for 2019.

Considering the continuously rising market price of an elite starting pitcher, the richest contract in Philadelphia professional sports history these days looks plenty reasonable. But over the winter, clubs were reluctant to take on the pitcher's deal in its entirety while also depleting their farm systems by parting with top prospects.

The Boston Red Sox and Texas Rangers have been the most-speculated suitors for Hamels. The Red Sox lack an ace and boast coveted young players in second baseman/outfielder Mookie Betts and catcher Blake Swihart. The Rangers lost their ace, Yu Darvish, to Tommy John surgery during spring training. They, too, have intriguing prospects.

Which teams enter the Hamels sweepstakes at the trade deadline will, of course, hinge on baseball's first-half results. A club expected to contend could unexpectedly falter, and one projected for the bottom of the standings could surprisingly surge.

But perhaps helping the Phillies is the lack of other topflight starters expected to be on the trade market. The coming free-agent class is loaded with starting pitchers, but most are with teams that are expected to contend. Cincinnati Reds righthander Johnny Cueto, 29, might be the only true ace who will be on the market this summer.

Hamels has been consistent in his stated desire to pitch for a contender. On the eve of spring training, USA Today published a story intimating that Hamels desired a trade and, regarding the notion of pitching for a contender, quoted him saying, "I know it's not going to happen here."

But just a few days later, in his first news conference of the spring, Hamels flipped the script and echoed the sentiments from the previous two days of fellow veterans Cliff Lee and Jonathan Papelbon. "You can't count us out," Hamels said that day. It was also revealed that his USA Today interview was a continuation of a conversation that began the previous month while he was on vacation in Hawaii.

"I have no control over a certain direction [of the organization]," he said this spring. "An organization, they have a bigger picture that they have to worry about.

"As a player, we really have to take the straight-and-narrow approach. We have a job to do, people are counting on us, and I think that's kind of what an organization, an upper management, has to worry about is what players are going to be accountable, what direction can we go with what we have. I'm just one piece of the puzzle."

What Hamels will face this season won't be dissimilar to what two of his former rotation mates faced in the past. Lee, traded four times before signing his five-year, $120 million deal with the Phillies in December 2010, heard his name in trade speculation in several recent Julys.

Roy Halladay faced constant questions throughout 2009, his final season with the Toronto Blue Jays.

"It is very tough, very tough," Halladay said during a visit to the Phillies' spring training complex in Clearwater. "I know for me, I had a lot of emotions. I felt like I had a few years left to try and accomplish things that I wanted to accomplish, and in Toronto they were going in a different direction than what I needed to go. That was very difficult."

Hamels experienced an uneven Grapefruit League slate, although most pitchers spend much of March working simply on locating their fastball. As Hamels' spring outings wore on, he started incorporating more and reeling off outs as usual. A March 26 start against the Toronto Blue Jays ended with five scoreless innings.

After not trading Hamels over the winter, the Phillies are taking the obvious risk of injury by holding on to him, likely for the next few months. He could also very well increase his value before June and July.

Amaro said this winter he did not feel pressure from the Phillies ownership group to deal Hamels.

"He's one of the best pitchers in baseball," the general manager said then. "And so, if we were to move him, we're going to have to get some of the best prospects in baseball back."

In any trade involving Hamels, the Phillies would look to bolster their pool of position-player prospects. They used last June's draft and the December trades of Jimmy Rollins, Marlon Byrd, and Antonio Bastardo to inject starting pitching prospects into the upper levels of their farm system.

Swihart emerged as the popular name this winter and spring. By the summer, several other prospects will surely emerge as potential trade pieces. If July 31 arrives and the Phillies decide to move forward with Hamels on the roster, the full ensemble of players needed for contention might not be in place before the end of his contract. If they deal Hamels, the Phillies can't afford to miss on their return, as they did in the December 2009 trade of Cliff Lee to the Seattle Mariners.

This much is clear: Six and a half years after pitching his way to World Series MVP honors, Hamels and his prized left arm also could prove key to the Phillies' future.

Playing Aces: Recent pitching stars dealt around the July 31 trade deadline

July 27, 2008: CC Sabathia. The Indians traded Sabathia to the Brewers for Matt LaPorta, Michael Brantley, Rob Bryson, and Zach Jackson.

July 29, 2009: Cliff Lee. The Indians traded Lee and Ben Francisco to the Phillies for Jason Knapp, Carlos Carrasco, Jason Donald, and Lou Marson.

July 27, 2012: Zack Greinke. The Brewers traded Greinke to the Angels for Jean Segura, Ariel Pena, and Johnny Hellweg.

July 5, 2014: Jeff Samardzija. The Cubs traded Samardzija with Jason Hammel to the Athletics for Addison Russell, Billy McKinney, Dan Straily, and cash.

July 31, 2014: David Price. The Rays traded Price and Austin Jackson in a three-team deal that netted them Willy Adames and Drew Smyly from the Tigers and Nick Franklin from the Mariners.

July 31, 2014: Jon Lester. The Red Sox traded Lester and Jonny Gomes to the Athletics for Yoenis Cespedes and Oakland's competitive balance Round B pick for 2015.

@jakemkaplan

Future Phils: Starting Pitchers

The accepted philosophy of most baseball development people is that you try to gather as many quality arms as you can and you hope some of them develop into frontline big-league starters. For proof of how infrequently it happens, we offer this statistic: Only nine pitchers who came through the Phillies farm system have made at least 20 starts in a single season in the 21st century and only five have made at least 30 starts.

In an effort to help their odds, the Phillies have made some recent trades for pitching. Here's a list of some hopefuls for future Phillies rotations:

Aaron Nola. The seventh overall pick in last year's draft immediately rose to the top of the minor-league depth chart and did not disappoint, posting a 2.93 ERA in 12 games with single-A Clearwater and double-A Reading. Likely opening-day destination: Reading.

Ben Lively. Great name for a pitcher, but the 23-year-old right-hander acquired from the Cincinnati Reds for outfielder Marlon Byrd relies more on deception and throwing strikes than an overpowering fastball. Likely destination: Reading.

Zach Eflin. The former first-round pick of the San Diego Padres came to the Phillies as part of the deal that sent Jimmy Rollins to the Los Angeles Dodgers. The 6-foot-4 right-hander turns 21 this month and has a fastball that sits between 93 and 95 m.p.h. He also throws a curveball and changeup. Likely destination: Reading.

Tom Windle. The 23-year-old lefty was a second-round pick by the Dodgers in 2013. He has some deception in his delivery and a fastball that sits around 92 m.p.h. He still needs work on command of his secondary pitches (slider and change-up). Likely destination: Reading.

Jesse Biddle. The team's 2010 first-round draft pick will try to get back on track after a dreadful 2014 season, which included a hail-induced concussion and elbow soreness in winter ball. Biddle is still only 23, but this is a vital season for the lefty from Germantown Friends School. Likely destination: Reading.

Severino Gonzalez. The Phillies did not let him throw his cut fastball early last season because they wanted him to develop his changeup. He struggled as a result. When given the pitch back in August, he posted a 2.53 ERA in five starts. Likely destination: Lehigh Valley.

Joely Rodriguez. After he posted an inflated 4.84 ERA with Pittsburgh's double-A Altoona affiliate last season, the Phillies acquired the 23-year-old lefty in exchange for Antonio Bastardo. His motion is similar to Bastardo's, but the Phillies will let him remain in a starting role at the beginning of this season. Likely destination: Lehigh Valley.

Matt Imhof. After a dominating junior season at Cal Poly, Imhof was selected in the second round last year by the Phillies. The 21-year-old lefty scuffled in seven starts at low-A Lakewood. Likely destination: Lakewood.

Franklyn Kilome. It takes a lot of projection to see this 6-foot- 6, 175-pound righthander in the big leagues some day, but scouts like what they've seen so far. Likely destination: Williamsport.

Ricardo Pinto. The 6-foot righthander flashed a power fastball and had tremendous command during his nine starts at Williamsport last summer. Likely destination: Lakewood.

- Bob Brookover