Fans searching for a barometer on the strength of the Royals’ farm system following last month’s trade with the Rays should keep an eye on Bubba Starling.

The Royals traded two top-five prospects and two other high-end minor leaguers to acquire James Shields and Wade Davis. General manager Dayton Moore said the farm system remains well-stocked, but how much of a hit did the Royals take?

“I wouldn’t say the cupboard is completely bare, but I don’t know if you’ll be able to serve a six-course meal anymore,” said Jonathan Mayo, MLB.com’s prospect expert. “Anytime you make a trade like that, it’s going to leave things a little more barren, especially at the top of the system.

“There is still some talent there. There are still some enigmatic pitchers that could turn things around. Then you have a guy closer to the bottom of the system like Bubba Starling that we have to wait and see what he turns into. He could end up being every bit as good as people think. It’s just going to take longer.”

Mayo said the Royals’ system still ranks in the top half of baseball, an assessment shared by J.J. Cooper, a writer/editor for Baseball America.

Cooper thinks the 2013 minor-league season will tell a lot about how deep their system is these days. He also used Starling as an example.

“Bubba Starling, for all the tools he has, there are a lot of questions about his hitting ability,” Cooper said. “Well, he could answer those in a good way or bad way. There are a lot of guys in that system who are intriguing, but there are not a lot of guys in the upper levels who you say (are) ready to help at the big-league level. That’s what they traded away in Wil Myers and Jake Odorizzi.”

Myers and Odorizzi were top-five prospects in the Royals system, while third baseman Patrick Leonard and pitcher Mike Montgomery were rated in the top 20.

Cooper believes the Royals would not have dealt that much talent had they not endured a bit of tough luck. In particular, the pitching prospects, once the strength of the system, have fallen on hard times.

“The reality is they probably don’t end up making that trade if not for the fact that the starting pitching prospects in the system they’ve had for several years are not healthy and in the big leagues,” Cooper said. “They’re either not healthy (Danny Duffy, John Lamb), or they have not developed, like Mike Montgomery or Chris Dwyer. If just two of those had developed and are healthy, they probably don’t feel the need to make this deal.”

However, should some pitchers rebound and others blossom, the Royals’ farm system could move back toward the top of the rankings.

Kyle Zimmer (the Royals’ top pick in last year’s draft), Yordano Ventura, Sam Selman and Jason Adam (out of Blue Valley Northwest) are all judged to be among the Royals’ top 10 prospects, according to Baseball America.

There are others who have fallen out of the top 10, like lefties Lamb and Dwyer.

“Is a guy like Dwyer going to be any good?” Mayo asked. “Will John Lamb come back? I heard reports that he was throwing very well. That would be a huge sort of addition if he can come back. Before he went down with the elbow (injury), he was one of the better left-handed prospects in baseball. They could kind of restock without having to do much if guys step back and return to form.”

Pitching aside, the biggest complaint of the Rays trade was dealing Myers. He was Baseball America’s minor-league player of the year and looked ready to fill a hole in right field.

Starling, the former Gardner-Edgerton High School star who was the Royals’ first-round pick in 2011, could follow in Myers’ footsteps.

“If you’re looking for a hitter, an impact player, it has to be Bubba Starling,” Mayo said. “(Third baseman) Cheslor Cuthbert, he might be OK, but Bubba Starling is the guy if you’re going to look at a guy in that system who could turn into that elite-level prospect, real impact player at the big-league level, he’s the guy.”