In all, 21 players will join the 40-man roster in big league camp. Pitchers and catchers are due to report to Scottsdale, Ariz., on Feb. 19, and the first full-squad workout is Feb. 27.
Arenado, who turns 21 on April 16, was ranked 22nd in the MLB.com Top Prospects report, released last week, after leading the Minors with 122 RBIs at Class A Modesto and earning Arizona Fall League Most Valuable Player honors. Bettis, who turns 23 on April 26, struck out 184 in 169 2/3 innings at Modesto last season. Although some have called Bettis the closer of the future, he'll attend camp as a starting pitcher.
Wheeler, 24,heads into his second Major League camp after hitting .284 with 33 home runs and 86 RBIs at Double-A Tulsa. Matthes, 25, batted .334 with 23 homers, 39 doubles and 95 RBIs at Modesto.
Moyer is making a comeback after missing 2011 because of Tommy John surgery on his left elbow. He went 9-9 with a 4.84 ERA for the Phillies in 2010. Moyer's 22-plus seasons of big league service time make him the most-experienced player in camp.
Ekstrom, 28, was 0-3 with a 5.36 ERA in 17 total relief appearances with the Padres (2008-09) and Rays (2009-10). Torres, 29, was 1-3 with a 6.86 ERA in 13 games, including six starts, with the White Sox in 2009 and 2010 and was 1-2 with a 6.26 ERA in six starts for Japan's Yomiuri Giants last season.
Nieves, 34, made 20 regular-season appearances with the Brewers last year and has hit .221 over eight seasons with the Padres (2002), Yankees (2005-07), Nationals (2008-10) and Brewers. Castillo, 27, hit .314 in 22 games with the Reds (2008-2009).
Harris, 31, has hit .260 with 29 home runs and 158 RBIs in 485 games with the Cubs (2004), Expos/Nationals (2004-06), Reds (2006), Rays (2007) and Twins (2008-10). Wood, 26, a top Angels Draft choice in 2003, has batted .186 in 272 games for the Angels (2007-11) and Pirates (2011). Brown, 26, hit .182 in 22 appearances for the Cardinals last season.
Also receiving camp invitations are right-handed pitcher Joe Gardner and catcher Matt McBride. That pair, left-hander Drew Pomeranz and right-hander Alex White formed the quartet of players the Rockies received last season when they sent their onetime ace pitcher Ubaldo Jimenez to the Indians in a trade.
First-base prospect Ben Paulsen will be making his second trip to big league camp. Other Minor League prospects coming to camp are right-handed pitchers Mike Ekstrom, Dustin Molleken, Rob Scahill and Josh Sullivan, and catcher Lars Davis.