Every year some fantasy owners' top sleeper or favorite prospect doesn't begin the season in the majors. It can be a real bummer, but there are a number of reasons players stay down on Opening Day. In some cases, they're just so good that their franchise wants to extend their control over the player. Other times they have major flaws to work on.

Here are the top five players starting the year in the minor leagues, and what to expect from them in 2015.

Kris Bryant, 3B Chicago Cubs

Without considering outside factors like team control, free agency and contracts, it's unfathomable that the Cubs would begin the 2015 season without Bryant on the big league roster. He has terrorized minor league pitching for two years, belted 43 home runs last year between Double-A and Triple-A, and hit .425 with nine home runs this spring.

There are concerns about Bryant's strikeout rate-28.6 percent in Triple-A in 2014-but the obvious reasoning for his demotion is service time. The Cubs have a potential star in their midst and they want to delay him from leaving or demanding big bucks for as long as possible. That said, if he keeps tearing it up he'll be up in the big leagues very quickly. When he does, expect him to hit a ton of home runs, and possibly rack up big RBI totals. He likely won't hit above .250, but that's alright if he can swat 30 home runs. I wouldn't predict 30, but it is within reach.

Javier Baez, 2B/SS Chicago Cubs

These guys sure do have some big-time prospects huh? Baez has big-time power which is especially valuable at middle infield spots. The problem is that he strikes out a ton-last year in 229 MLB plate appearances he was set down on strikes more than 40 percent of the time while hitting a putrid .169. He also smacked nine home runs.

Baez showed similar strikeout tendencies this spring, which is why he somewhat surprisingly didn't make the big league roster. Unlike Bryant, Baez seems to have further to go in his development before his power potential isn't completely swallowed up by his inability to make consistent contact. If you drafted Baez in a keeper league, you could hold on to him, but if the league is shallow the recommendation is to drop him and keep your eyes peeled.

Carlos Rodon, SP Chicago White Sox

Rodon is a hefty left-hander with big stuff. His spring training performance looked good enough to be brought up; he whiffed 21 batters and walked five, went 2-0 and posted a 3.06 ERA. Chicago has a four-man rotation right now per RosterResource.com, so the decision to send Rodon down is likely closer to a Bryant situation.

The White Sox are in arguably the toughest division in MLB this year though, so as long as Rodon doesn't falter in the minor leagues he should be brought up no later than mid-May, if not earlier. Once he hits the bigs, he should be a good source of strikeouts, but his WHIP may not be pretty. He has shown some control issues in his brief minor league career, so there may be implosion games. He'll be a back-of-the-rotation type for fantasy in 2015, but makes for a very solid keeper option.

Jon Gray, SP Colorado Rockies

Gray has a bigger minor league resume than Rodon does, going 10-5 in 24 Double-A starts last year with a 3.91 ERA and 1.19 WHIP. He's a big-time prospect so he might be subject to the Bryant treatment, and the Rockies would be more justified than the Cubs in their decision to hold him back after a tough spring. Gray is 0-2 with a 5.93 ERA this spring, and surrendered 15 hits in 13 innings.

Colorado is short on pitching, so we will see Gray at some point. When he comes up expect a similar forecast as Rodon, with good strikeout numbers but questionable control. He may also be homer-prone at Coors Field.

Addison Russell, SS Chicago Cubs

Yup, another Cub. Russell is one of the game's biggest prospects and he tore it up this spring, hitting .324 with a home run, six RBI and two stolen bases in 12 games. Russell is a power and speed threat, but he's only got 50 games at Double-A under his belt, and he's currently being blocked at the MLB level by Starlin Castro, and in Triple-A by Baez. Baez can simply move over to second base, but it doesn't make sense to promote Russell if he won't play every day.

Dynasty leaguers should feel free to draft Russell for his future potential, but don't expect him at Wrigley Field in 2015, unless it's as a September call-up.