The midfielder spent part of last season on-loan at Middlesbrough.
"After Josh's experience at Swansea, when he didn't really play, the main thing with him was that we wanted him to accumulate games. From that perspective it was a success; he played almost 40 games," Holland told chelseafc.com.
"When Middlesbrough were doing particularly well in the first half of the season, he was also doing well. The team tailed off after Christmas and his form coincided with that a little bit. It's difficult sometimes for a young player in that situation but, having said that, there were enough positives to suggest Josh is a player heading in the right direction and will benefit from having a full season at Championship level.
"The Championship is a very good development league for our young players, there are some big clubs and they play 46 games. Physically they get pushed, they play twice a week for most of the season, which you have to do if you want to play for Chelsea, so it's been a good experience for Josh and hopefully there's a bit more to come from him."