The 23-year-old did not quite meet Deila's standards at the start of the campaign, with the Celtic star far from the first name on the Norwegian's team sheet at times this term.
But the two have since spoken at length, with the Celtic boss outlining exactly what he expected from the midfielder.
And, now, Deila is full of pride at the improved performances the 23-year-old has delivered this season.
RD: "He’s an important player for us and has really stepped up his game. I’m proud of his performances this season."— Celtic Football Club (@celticfc) March 12, 2015
Bitton has recently been out injured for the Bhoys and is not a certainty for Sunday afternoon's Scottish League Cup final against Dundee United.
Deila, though, is hopeful the young midfielder will be ready for the showpiece event, as Bitton himself is determined to feature in the clash.
RD on Nir Bitton: "Nir is hopefully ready. It’ll be a challenge up to the last minute but he’s very determined to play."— Celtic Football Club (@celticfc) March 12, 2015
Celtic will definitely be able to call upon Dutch defender Virgil van Dijk, whose sending off against Dundee United in the Scottish Cup quarter-finals last weekend has been rescinded.