The Phillies signed Franco out of the Dominican Republic back in January 2010, giving him a bonus of $100K. He debuted later that year for the Phillies' Gulf Coast affiliate, hitting .222/.292/.330 with two home runs in 51 games there. The Phillies moved him up to their short-season affiliate in the New York-Penn League in 2011, and after 42 games there promoted him to full-season ball. A fairly disastrous 17 game stint there ended with a return to Williamsport for the last 12 games of the year, as Williamsport fell just short of a playoff spot.
Franco moved up to full-season Low-A in 2012, and after struggling for the first three months of the season, hit .356 with seven home runs in the last two months. His overall performance ended up looking pretty good, as he finished with a .280 batting average, 14 home runs, and 32 doubles on the year. He moved up to High-A Clearwater to start the 2013 season, and promptly tore apart the league over a 65 game stint there as a 20-year old. He continued that tear after a midseason promotion to AA Reading, and finished the season with 31 home runs, a .320/.356/.569 slash line, and 36 doubles over 134 games.
He spent most of last season with AAA Lehigh Valley, and was very inconsistent with his performance in the first half of the season, hitting .172 in April, .282 in May, and .162 in June. He clearly made some sort of adjustment as the season wore on, as he hit .324 in July and August with 11 of his 16 home runs in the minors. He was called up at the end of the season by the Phillies, appearing in 17 games in the season's final month.
Franco could very well see more time in AAA this year, both in part because of the potential to get another year of team control for a Phillies team that is expected to be near the bottom of the standings from Opening Day, and also to continue to work on some additional improvements. There are questions about his defense at third base long-term, and while he has improved substantially over the past couple seasons, may not be an average defender long-term.
In terms of the current roster, there are really two players that are keeping him from a full-time job in the majors. The current third baseman, Cody Asche, hit .252/.309/.390 with 10 home runs last year for the Phillies, and while they're not ready to give up on him, he's not likely to be an impediment to Franco when Franco is ready (he was not in our consensus top 30 for 2015, either). To this point, the Phillies have been working with Asche in left field, potentially giving him more flexibility and giving the team the option to keep another low-cost option for another season or two. Over at first base remains the albatross of a contract, with Ryan Howard owed at least another $50 million for this year and next. While there have been discussions of trying to trade Howard or even potentially releasing Howard, it seems unlikely that the Phillies would release him unless he struggles even more than he did last year.
The questions about Franco's long-term spot on defense will drop his value somewhat, as he will need to hit better to provide more value to fantasy owners if he is only a first base option. With that said, the upside is still there for a valuable contributor at either position, as Franco could provide a .280+ batting average with 25+ home runs on a regular basis. He's a well-below average runner, so consider yourself lucky if you get more than 1 or 2 steals per season from him, if that. He should also see solid matching contributions in both runs and RBI, and has the potential to be a top 10 option at third base in a full season.
The most realistic thing to occur in my opinion is that Franco goes to AAA for the first month or two of the season, and is up by the All-Star break to stay. At that point, we should know whether the team can play Asche in left field, or if Howard has become unplayable and relegated to a bench role. By then, Franco is hopefully crushing AAA like he was when he was called up last year, and makes it a tough decision for the Phillies. I would not necessarily advocate drafting him in shallow redraft formats this year (unless his role becomes a lot more clear during the Spring), but would absolutely grab him late in NL-only and deep mixed formats. If he's up for half a season, he could provide 10-15 home runs with a .250-.260 batting average fairly easily, more than returning late round value.