The Arizona Fall League is a well-respected destination for many would-be big leaguers, and several current Padres -- including Chase Headley and Cameron Maybin -- played there.
The league consists of six teams that play in six Cactus League stadiums beginning on Oct. 9. The season ends with a championship game on Nov. 17.
For many prospects, like Spangenberg or Liriano, the Fall League experience is a chance to be exposed to a higher level of competition while continuing to polish their skill set.
"For Liriano, it will be a good test for him against a little better competition, little different environment," Padres manager Bud Black said. "Same with Spangenberg, just keep playing, keep getting repetitions."
For those, like Kelly, who seem on the cusp of extended stints at Triple-A or even the big leagues, it's all about getting more innings and more repetitions.
Kelly, in particular, will head to Arizona to build on a 2012 season that saw him miss significant time with a right elbow ligament strain suffered after just two Triple-A starts. He returned in August, and will head to Arizona after September with the Padres in order to build his innings count closer to 100, but not necessarily in order to make a huge jump forward in 2013, unless the organization feels he's gotten enough work in before then.
"I think I'd be going to get more innings, just because I might end up under one hundred innings after this year, and I don't want to be behind heading into next year," Kelly said. "We'll see how the rest of the season goes, and then if I need more innings at the end of the year, then I'll go there to pitch."
Lefty Robbie Erlin also missed three months with elbow issues, only returning in August, and is headed to the AFL for the same reason Kelly is: to try to make up some of those lost innings.
"I think for Casey and Robbie, you're talking about two starting pitchers who, the majority of their season was interrupted, so this gives them a chance to go down and pitch," Black said. "They'll continue to work on the things they need to work on, get arm strength, get their innings up."