RHP Casey Kelly needs Tommy John surgery, leaving a hole in the San Diego Padres’ rotation and adding to the club’s woes as Opening Day nears. Just a few days earlier, 3B Chase Headley suffered a thumb injury that will keep him out for 4-6 weeks, which takes a big bite out of the batting order.

Throw in Yasmani Grandal’s 50-game suspension for PED use and you have some key components missing from a club that is trying to catch up to the defending World Series champs in San Francisco and the star-laden Dodgers, not to mention Kirk Gibson’s Diamondbacks club that won the NL west in 2011.

Here’s what the Padres are tasked with replacing, at the least:

KELLY – Only 6 starts in 2012, with just 29 IP and 26 K’s, but the organization’s top prospect (Baseball America) was expected to continue maturing into a starter role near the front of the rotation. He was slated for the fifth starter spot this season but Kelly was a key piece in the trade that sent Adrian Gonzalez to Boston.

HEADLEY – After several seasons where he flashed great potential, Headley had a second half for the ages in 2012 and ended up the year with career highs in hits (173), HR (31), RBI (131) and all three slash line stats (.286/.376/.498). Always solid in the field, the bat performed at a level that drew MVP consideration as Headley finished 5th.

GRANDAL – In 226 PA, Grandal went .297/.394/.469 with 8 HR and 36 RBI. Coming over from the Reds in the Mat Latos deal, Grandal ended up supplanting Nick Hundley behind the plate.

With the Giants winning two of the last three World Series, most fans barely remember that they only got into the 2010 postseason by running down the Padres, who had been in first place for much of the year. Well, Bruce Bochy’s club is back with all of their key players intact.

The Dodgers, under new ownership, have started up a friendly little contest with Congress to see who can spend the most money. It has netted Don Mattingly’s team many high-priced stars including Gonzalez, Zack Greinke, Josh Beckett and Hanley Ramirez. The Dodgers finished 10 games over .500 in 2012 and that seemed like a disappointment after being in first place for much of the season. The Greinke addition was the big acquistion over the offseason and continued to show that the new ownership is all-in to win now.

The Diamondbacks were talented enough to race past the Giants in 2011 and fiery skipper Gibson is still running the show. Despite the loss of Justin Upton, the Snakes are still talented and, under Gibson’s direction, a very gritty club that can’t be overlooked.

That is what the Padres are up against. And the other division rival, Colorado, has a couple of guys known as Tulo and Cargo back in the middle of the order.

With a modest payroll, the Padres need production anywhere they can get it to keep up with the heavyweights. Losing Grandal, Kelly and Headley are setbacks of varying lengths that could end San Diego’s 2012 season before it starts.

But it isn’t all doom and gloom in America’s Finest City.

Despite the setbacks , manager Bud Black’s club is getting solid contributions this spring that could offset the absences of these key players. At the catcher position, Grandal’s suspension has opened the door for former starter Nick Hundley. Hundley has taken advantage so far with a .425/.452/.750 line. Always a solid backstop, Hundley had career highs of .288 batting average and 9 homers over 308 PA in 2011.

In the battle for starting rotation positions, the Padres also have a pleasant surprise in RHP Tyson Ross. In 21 IP, Ross has fanned 19 batters while walking 10 and his ERA sits at 2.57 after 6 outings. What Kelly was going to contribute is obviously unknown as he was looking to establish himself at the major league level. But Ross is making a strong bid to fill the hole created by Kelly’s injury.

And with Headley out, even for just a couple of weeks of regular season play, San Diego loses his defense at 3B and his potent bat. Fortunately for the Padres, they have some depth in the infield. With Yonder Alonso holding down 1B, the Padres have Alexi Amarista, Everth Cabrera Logan Forsythe and Jedd Gyorko available for the remaining infield slots. Cabrera is the starting shortstop so Amarista, Forsythe and Gyorko are the other moving parts. And Gyorko, the club’s #3 prospect according to Baseball America, is having a good spring while moving into the 3B spot.

While Gyorko may hold down the hot corner and his bat has some pop, Headley’s offensive output from last year will be hard to match. The Padres have another spring surprise that could address the power issue. The big bat of big Kyle Blanks is alive so far and posting impressive numbers. In 64 PA, Blanks has a line of .346/.438/.577 with 2 HR and 12 RBI. It has been start-and-stop for Blanks since his first pro season in 2005 because of annual injuries but the raw power has tantalized baseball observers all along. In this year’s Cactus League play, Blanks is hitting consistently and may yet prove to be the bat big enough to put up solid power numbers in spacious Petco Park.

The headlines have been pretty dire for the Padres as they have moved toward 2013, but there has been a silver lining to at least some of the setbacks. The club will be without Headly for a couple of weeks, Grandal for 50 games and Kelly for the whole season. Can the likes of Ross, Hundley, Gyorko and Blanks make up for them, or even improve on the production that the Padres would have gotten? Time will tell. But there is little margin for error in the NL west. Bud Black will be playing high-stakes chess all season long, no matter who he has available.