It's never easy for a team to move on from an established star player. Especially when that player is a four-time All-Star and four-time Gold Glove winner.

FanGraphs, Pedroia is a top 35 second baseman if we sort by each player's fWAR. Pedroia's 40.7 fWAR is even more impressive when you factor in that he's compiled it over the course of just 1,224 games, so we could see that improve even more with a few more years of service.

Two other impressive notes for Pedroia from the table linked above -- his slugging percentage of .443 ranks 20th all-time among second basemen, and he's also one of just 27 second basemen to hit at least 100 home runs and 300 doubles in their career.

Dustin Pedroia has also been pretty good since his rookie year in 2007, placing well in all categories of second basemen that have logged at least 900 games since 2007.

As we look at the counting stats, it's a mixed bag. His 113 home runs aren't as many as Chase Utley or Robinson Cano, ranking 10th out of 17 qualified players. But his 126 stolen bases rank third and his RBI total is the sixth best among second basemen.

The stats get better for Pedroia though -- his slash line over the last eight seasons is excellent, as his average is tied with Jose Altuve, his on-base percentage is tied with Utley for second and his .446 slugging percentage is fourth, behind Cano, Utley and Jeff Kent. Offensively, Pedroia brings a lot of value, as his wOBA is third and his wRC+ is fourth. And he ranks second in both fWAR and nERD (which shows how many runs he adds over an average player).

This season, Pedroia is still providing plenty of value -- he's tied for third in home runs among all second basemen, and his .292/.354/.431 slash is still one of the best in the league. He also has top-11 numbers across the league as a second baseman in wOBA (.343, 5th), wRC+ (117, 5th), fWAR (2.0, 10th) and nERD (1.16, 11th).

So what exactly has planted the idea of trading Pedroia?

Waiting In the Wings

The Red Sox seem to know what they're doing in their farm system -- Xander Bogaerts rose through the system in three years, while Mookie Betts only took two years to move up the ladder. And Hanley Ramirez was a top-10 prospect for the team until he was traded in 2005.

This (and last) season, it's been the second basemen in the farm system that have started to turn heads. Of course there's Yoan Moncada -- Boston's $63 million man -- in Greenville for his first season in a professional league, but it's more than just him in the system. The AA and High-A teams have a pretty solid prospect manning second base as well.

Let's start with Carlos Asuaje. He spent time in Low-A as well as High-A last year, hitting 15 home runs and 101 RBI, ending his season in Salem with an excellent slash (.323/.398/.516) and a .403 wOBA. Asuaje also brings positional flexibility to the Red Sox as he's manned second, third and shortstop as well as left field so far. However, in Portland, his hitting has slowed some with just four home runs and a noticeable dip in his slash line.

Wendell Rijo moved from Greenville to Salem this season, but has already regressed from a season that was a little above average in Greenville. If Rijo fixes some consistency issues, he could provide a valuable bat in the minors, but little value elsewhere.

Yoan Moncada is the big story though -- and don't be fooled by his .274 average. After finishing barely above the Mendoza Line in the first half of the South Atlantic League, Mocada has put on quite the show the past 20 days. In just the month of July, he's hit 3 of his 4 home runs, 10 of his 21 RBI and swiped 9 of his 18 stolen bases. His slash in the first 20 days of the month has been .343/.427/.571, showing why Boston wasn't afraid to invest millions into such a young player.

So with some facts presented for Dustin Pedroia and for those that man his position in the minors, let's state the case for why and why not the Red Sox could look to trade Pedroia.

The Case for the Trade

There are plenty of replacement options for the Red Sox if they did decide to trade Dustin Pedroia. At the Major League level, Brock Holt has filled in admirably when Pedroia has sat or been injured. Then there's phenom Mookie Betts, who played second base early in the minors and some would say it's a more natural position for him.

By using either player, the Sox will likely alter their plans for their second basemen in the minor leagues. It's hard to say if Carlos Asjuae or Wendell Rijo would be ready in the next year or two, but a combination of them and Holt could be just what the Sox need until Yoan Moncada is ready to play. According to most scouts, Moncada could be up by the 2017 All-Star break, if not sooner if he's fast-tracked through the minor league system in 2016.

It could be a big risk to rely on so many prospects, but by moving Pedroia, the Sox have payroll flexibility too -- Betts, Moncada, Bogaerts and others could command a big pay day in a few years. If money is tied up with an aging Pedroia, the Red Sox may not be able to hold onto everyone they like.

The Case Against the Trade

There are a lot of things the Red Sox have to consider with Dustin Pedroia and any potential trades. First is his value, as 20-25 teams don't have a second baseman that is better than Dustin Pedroia right now. How many of those teams want an upgrade at the position? Of those teams, how many have something to offer for Pedroia that would be of value to the Red Sox right now?

Something that isn't quantifiable is the atmosphere and leadership that Pedroia brings to the clubhouse. It's not saying that it can't be replaced, but how much time would that take to transition to another player? A young team is always in need of strong, veteran leadership that the Red Sox may value over prospects within the system.

And who is to say that these prospects pan out? Asuaje could become a star in his own right, but his tools project him to be no more than a utility player -- and the Sox already have someone in that role currently. Rijo should fit ok at second base, but it will be his bat that gets him a spot on a major league roster, not his defensive skills.

And of course there's the millions that were handed to Moncada. He could continue to pick up the pace as he works his way up the ladder in the system, but he may be shifted to an outfield position in the higher levels to see where else he could play given the potential of his tools. Boston did that with Mookie Betts and it's worked out very well. A successful shift to the outfield would force Boston to then keep Pedroia.

Final Thoughts

So will we see Boston trying to sell Dustin Pedroia as the trade deadline approaches? Anything is possible, but Pedroia has been outstanding for the Red Sox and his value is very high at the moment. A team would have to put together an excellent package to pull him from the Sox, all while being willing to take on the six remaining years of his contract.

Thankfully for the Red Sox, Pedroia's no-trade clause hasn't kicked in yet (it will though at the end of 2016 thanks to the 10-5 rule). After this time next year, Pedroia's contract would allow him to refuse any trade once he's hit 10 years of service in the major leagues since he's played his whole career in Boston.

So while a trade of a clubhouse leader and key contributor seems unlikely, and current replacements could dramatically change the work that is going on in their farm system, it may be the perfect time for the Red Sox to consider trading Pedroia while his value is high and he can't shut down any trade.