Martin went with Charlie Taylor at fullback for last week's draw with Ipswich.
He said: "Leaving Kyle out after what he has done for us is not easy but Yuki has been one of our best players at right-back.
"We did feel we wanted some balance in the team and having a natural left-footer helps us out a lot.
"I thought Charlie was great - he played two games last week and will get better and better. We also have Ryan Manning who can't get in the squad.
"It was about balance in the team. We don't have many left-footed players on the pitch at the moment. I think Charlie was probably the only one.
"We had to adapt for that game. We might need to do that against Bournemouth.
"Kyle is ready to play. He understands the reason. People try to bring his contract into it - that wasn't a problem with Che and Stuey.
"That will never be a problem. It will be about trying to win a game and have the best players on the pitch.
"We have six, seven, eight guys not in the squad. Some of those are internationals. It's not easy.
"We work relentlessly with everyone to keep them ready. Someone can come into the lineup having not been in the squad - as was proven at Everton.
"Someone can go from starting to not being in the squad. It all depends on what we feel we need for each game on the bench."