According to Ed Aarons of the Guardian, Chelsea have "already agreed personal terms" with the Ghanaian, but the Bundesliga outfit are "holding out for €30 million."
As Aarons notes, the youngster would be utilised as a replacement for Filipe Luis, who returned to Atletico Madrid earlier in the summer.
The 21-year-old impressed for Augsburg last season, as WhoScored.com illustrates:
Abdul Rahman Baba: Made more tackles (109) than any other player in the Bundesliga last season
— WhoScored.com (@WhoScored) June 26, 2015
The left-back also showed his qualities in the air and getting forward, with Squawka reporting that Rahman won 67 per cent of his aerial battles and successfully dribbling past an opponent in 66 per cent of his attempts.