The Chicago Cubs are one of the most popular franchises not only in Major League Baseball but also in the sports industry. But that hasn't always translated into success on the field, and this season is living proof of that.

The Cubs are going through a rebuilding phase. That's a process that takes time and gets worse before it gets better most of the time. It's also a test of the fans' patience and perspective, but it's something every team must go through every now and then.

Needless to say, that means making tough decisions and letting go of some of the biggest names on the squad. With that in mind, we'll take a look at the 3 Cubs stars most likely to be traded this season.

MLB Trade Rumors: 3 Cubs Stars That Will Be Traded This Season

3. Willson Contreras

Willson Contreras is the Cubs' leader on and off the field and perhaps the most iconic player left from their World Series run. He's set to become a free agent at the end of the season, and contract extension talks have halted.

Contreras should have no trouble finding a new home. He's one of the best hitters at his position, and the universal DH spot helps him stay fresh and healthy. Thus far, he's slashed .274/.392/.890 with 13 homers and 35 RBIs.

2. Ian Happ

Ian Happ's defense is pretty much average, but he brings versatility to the table that most contending teams should consider ahead of the postseason. He can play all over the diamond and in the outfield as well without being a defensive liability.

On top of that, Happ's offense has been pretty decent this season. He's slashing .282/.378/.833 with eight dingers, 38 RBIs, and six stolen bases. He's on a team-friendly deal and should gauge plenty of league-wide interest.

1. David Robertson

In a league where reliable relievers are a dying breed, David Robertson has turned back the clock to have one of his best seasons up to date. He's 37 years old already, but he'd be a massive pickup for a team with World Series aspirations.

The former champion has been lights out for the North Siders this season. He's posted an ERA of 1.89 with a 0.960 WHIP, a 3.0 strikeout-to-walk ratio, and 45 strikeouts over 33.1 innings of work.