It's not easy to stash a Rule 5 guy in a major league rotation for a full season, so any team that looks at Rodriguez is likely to use him as a long man out of the bullpen.
Considering the other pitching prospects that the Phillies have, losing Rodriguez wouldn't be devastating, but certainly, they'd rather not lose a young pitcher with big potential.
Juan Sosa (RHP) - Sosa may have more potential than Rodriguez in the long-run, but he's already older (23) and has only pitched as high as Clearwater, so there's more uncertainty about how he might do at the major league level. He's also not coming off of his most impressive season, posting a 4.26 ERA while he had a 2.83 career ERA coming into the season.
The upside is that he's pitched primarily as a reliever throughout his minor league career, he gets groundballs and he struck out just under one hitter per inning last season (79 K/80.1 IP). Sosa also has more velocity than Rodriguez, throwing his fastball in the mid-90s and has a nice sweeping curve that can make hitters look pretty weak.
It's very possible that somebody will take a chance on Sosa.
Justin Friend (RHP) - You can't be more lights out than Friend was at AA Reading in 2012, posting a 0.23 ERA in 38 outings, with 24 saves. He came up to AAA Lehigh Valley though and found that it wasn't quite as easy at that level (4.40 ERA in 12 games). That shouldn't scare off other clubs too much, because most Rule 5 options haven't pitched much at all at AAA and Friend at least has some experience at that level.
In 330 1/3 minor league innings, Friend has 352 strikeouts and has done that with just basic stuff. None of his pitches are above average, but all of his pitches are getting better, which is the key for Friend. It also doesn't hurt that he commands them well and doesn't allow his pitches to get up in the zone, which has limited opposing hitters to just three home runs over Friend's last 113 innings of work.
He doesn't project as a top-level back of the bullpen type, but could well be a worthwhile risk for a team that would pick their spots on how they use him.
Colby Shreve (RHP) - While there isn't anything that makes scouts drool over Shreve, he's been able to have success in the minors. He does have one thing that teams like to see in a potential Rule 5 pick; he gets groundballs. If Shreve can translate that little gem of success to the majors, he can easily become a decent find for a team looking for a guy to stash in the bullpen.
Jiwan James (OF) - This is a tough guy to gauge. He's got a lot of athleticism and can make amazing defensive plays. There's nothing about his offensive numbers that really stands out and he even fell just short of a .300 on-base percentage in 2012, which for a speed guy is a sin.
As for that speed, James definitely has speed, but he's not a great base stealer, having been successful on just 62% of his attempts and stealing just eight bases on sixteen attempts in 2012.
Having said all of that, because he does have some speed and can play defense, it's not out of the question that another team grabs James to give him a look.