As phenoms go, Cubs’Castro still under construction

The Cubs didn’t stencil a “FRAGILE” sign on shortstop Starlin Castro last year.

But in equally bold letters, they might as well have tagged him with one that read, ‘HANDLE WITH CARE.”

The Cubs did not allow their phenom to break camp with them in 2010 — they sent him back to minor-league camp after he went 15-for-35 (. 429) in 16 Cactus League games.

Instead, the Cubs opened the season with Ryan Theriot at shortstop.

A combination of factors finally forced the Cubs to go down to Class AA Tennessee to get the kid on May 7: a lackluster 13-16 record and an organizational belief that Theriot no longer could play shortstop effectively.

Castro’s debut was a spectacular one. He hit a 3-run homer in his first big-league plate appearance and later added a 3-run triple. The 6 RBI were the most recorded by a player in his first major-league game.

He played almost every day the rest of the way, but there were bumps along the ride.

Shortly after Mike Quade took over as manager, he benched Castro for three games after a lapse in concentration. But at the end of the year, Quade made sure to preserve Castro’s .300 batting average and send the kid out on a high note.

The expectations are no less for Castro this season. He turns all of 21 on March 24, and he’s the most exciting position player the Cubs have developed and sent to the big club in years.

Here are the key issues:

Defense:Believe it or not, some people with the Cubs last year felt they had the wrong scouting report on Castro. That is, they thought he would field much better than he would hit.

Turned out it was the other way around.

Castro turned in a hitting line of .300/.347/.408 with 3 homers and 41 RBI. He also committed 27 errors and had more than his share of problems around the bag.

Concentration:Quade wanted Castro to sit on the bench and watch for three games last September. Naturally, the subject came up again this spring.

#147;You give a guy a little breather and let him watch,#148; Quade said. #147;That#146;s taking a little pressure of a guy for a day or two. There are so many things that go into that. That didn#146;t happen because he thought he had it licked. There was so much, so fast, that#146;s so important for this kid. Sometimes you think, #145;Maybe it#146;s a little too much right now, and maybe this is a good thing,#146; and it gets taken as discipline or whatever. It really wasn#146;t. I really thought it was teaching moment for the kid to step back.

#147;The question becomes, #145;Is he not hustling. Are the mistakes lazy mistakes? Indecisive mistakes?#146; And not just for Cassie, for anybody. But I think a mental lapse that he would have from time to time, and that, to me, is a whole lot different than physical.#148;

Just last week, the Cubs had Castro do some extra defensive work to simulate game speed in practice.

#147;He#146;ll work, and we#146;ve got good people pushing him,#148; Quade said at the outset of spring. #147;And I mean instructors, by that, as well as players. That#146;s the only way he#146;s going to get better. He#146;s got work to do, that#146;s for sure.#148;

Offense:The Cubs believe Castro will continue getting better offensively, although it#146;s difficult to say how much power he#146;ll develop. He hit a combined 4 homers last year between the Cubs and Double-A.

Castro walked 29 times and struck out 71 in 463 at-bats. That#146;s a walk percentage of 5.7 and a strikeout percentage of 15.3.

He had a batting average on balls in play (BABIP) of .341, well above the league norm, which is around .300. Some stats-oriented people don#146;t expect Castro#146;s BABIP to drop drastically because of his speed and contact ability.

Colorado#146;s Troy Tulowitzki is considered by many the best shortstop in the National League. His hitting line last year was .315/.381/.568 with 27 home runs. His walk rate was 9.1 percent, and his strikeout rate was 16.6 percent.

If Castro can up both his on-base and slugging percentages, he could become an elite offensive shortstop.

One interesting fact pointed out by fangraphs.com is that Castro#146;s 31 doubles last year were more than those recorded by star shortstops Hanley Ramirez of Florida, who hit 28, and Derek Jeter of the Yankees, who had 30.