The Colorado Rockies may be entertaining offers on a pair of franchise cornerstones.

According to FOX Sports' Ken Rosenthal, the club is "willing to listen" to trade offers for shortstop Troy Tulowitzki and outfielder Carlos Gonzalez.

The pair represented one of the more formidable one-two offensive punches in the majors at the beginning of the decade, but injuries have slowed both players in recent years.

Tulowitzki has been named an All-Star in four of the past five seasons and is still one of the best-hitting shortstops in the game.

He posted a career-high .340 average in 2014, but was limited to just 91 games after injuring his hip. 

The knock on Tulowitzki, though, is not a production concern, it's health. The 30-year-old has missed an average of 56 games over the past five seasons, fluctuating from a low of 47 in 2012 to a high of 143 in 2011. 

Over that span he's hit above .300 four of five years. He had hit 25 home runs or more in four of the past six seasons and 90-plus RBI four times between 2007 and 2011.

He is under contract until 2021 on a deal that could pay him up to $129 million over that span, including $20 million in each of the next five seasons. That marks a $4 million increase from his 2014 earnings and is double what the Rockies paid him in 2013.

Gonzalez, 29, led the National League in hits in 2010 with 197 and also chipped in a career-high 34 home runs and 117 runs batted-in that season. He signed a seven-year, $80.5 million contract extension in January, 2011 that keeps him under club control until the end of 2017.

However, Gonzalez' salary rises significantly over the next three seasons, jumping from $10.5 million in 2014 to $16 million and $17 million in 2015 and 2016 respectively. He is owed $20 million in 2017, the final year of the deal.

The problem is that his health and production have both declined in recent years. The 145 games Gonzalez played in 2010 still represent a career-high. He played a career-low 70 games in 2014, producing a batting average of just .238 with an OPS of .723 (down more than 200 points from his 2013 mark of .958). He also posted a -0.7 WAR, slipping to the wrong side of the ledger from a 4.8 in 2014 and a 5.9 in 2010.

Gonzalez, like Tulowitzki, is coming off major surgery having undergone a procedure on his knee this past season.

Speaking about the contracts and health concerns, Rosenthal told the MLB Network that trading the pair poses not only a challenge for the Rockies, but also signifies a major philosophical shift.

"When you look at those two things together, along with what Colorado would want - there not going to want to simply dump these guys, they're going to want to make significant trades - I'm not sure anything is going to happen anytime soon," Rosenthal said.

"The significance is, until now, we have heard consistently from that team and from the owner in particular, Dick Monfort; 'we're not trading these guys. They're ours. They're ours forever.'" Rosenthal added. "This is the first sign of a departure from that philosophy... The first sign that they are at least willing to listen and entertain the idea of trading one or both. And, frankly, we'll have to see where this goes."

"Given the demand for offence in today's game, I would be surprised if nothing happens."