De Villiers said this is because of the limited amount of time they spend together and constant squad rotation in the short format.
The Proteas' one-day captain was speaking in Durban on Wednesday where the team was preparing for the first of two T20 Internationals against Pakistan starting on Friday.
South Africa are ranked number one in the world in the five-day game, while they sit fifth in 20-over cricket, one place above the tourists, who they whitewashed 3-0 in the Test series, and are placed fourth on the ICC's 50-over table.
“What's happened in the Test squad shows you that if you have a bunch of players together for such a long time, guys coming in just sort of fall into the system straight away,” De Villiers said on Wednesday.
“Everyone knows exactly what's going on. That's something we're still working towards in the ODI and T20 set-up.
"I wouldn't say we're very far off, but if we have a bit of consistency in selection over the next 12 to 24 months. I truly believe the results will start to show.”
'Giving youngsters a chance'
The national selectors rested key players during the recent T20 series, instead opting to reward promising performances on the domestic scene with a place in the Proteas team.
“It is a nice way of giving youngsters a chance to showcase their talents,” De Villiers said.
“I definitely see why that's happening. They're also the guys who do perform domestically and probably are the best T20 players in the team at the moment.
“But we haven't played a lot of cricket together as yet. It makes it tough that we change around a lot, there's no proper feeling for each other yet, but we're getting there.”
The 29-year-old, a veteran of 44 T20 Internationals, at an average of 22.34 with the bat, also conceded that his own form was suffering due to the lack of consistently playing the format.
“I haven't really found my rhythm yet in T20 cricket internationally. I'm still finding my way, where exactly I've got to bat.
"I mean, I'm a finisher in the middle order, top three maybe."
Consistency
“I feel we haven't played a lot of T20 cricket. It's difficult to find your way because your just play one or two in a series, three to four months down the line you play another one, then another two, so you can't get going.
“I don't find adapting to the format or any one of the three difficult, but finding your way in T20s, really getting into your rhythm and scoring a lot of runs is quite hard.”
De Villiers, who revealed that he may keep wicket in the series, also warned that Pakistan would provide a different challenge in the T20 game compared to the sorry one that was thumped in the Tests.
“They are definitely a better team when it comes to the shorter versions,” he said.
“They've showed that over many years now. They usede to be quite inconsistent, but they've shown that they can be a lot more consistent over the last two years.
“I think it's going to be a great series and a great way for us to challenge ourselves going forward.” – Sapa