As Chief of Surgery, Derek was looking for a new Head of Cardiothoracic Surgery as he believed Teddy Altman was still looking to leave the hospital as soon as her contract ended. Tom Evans, a brilliant cardiothoracic surgeon, spent a day at the hospital on Derek's request and worked together with Cristina. Cristina was blinded by his brilliance and didn't even notice that Tom didn't even allow her to hold the retractor.
When Teddy pointed this out and said that if Tom was in, she was out, Cristina felt torn between the two surgeons. She was convinced however that she was going to learn more from Teddy than from Tom, and asked Owen to convince Derek to offer the position to Teddy. Owen, however, felt that it was an opportunity for him to have Teddy fired, so he wouldn't have to decide anymore between her and Cristina. He convinced Derek to offer the position to Tom, but Tom rejected the offer.
Tom is a brilliant cardiothoracic surgeon at Baylor University Medical Center. He once visited Seattle Grace Mercy West Hospital when he was offered the position of Head of Cardiothoracic Surgery, but he declined the offer.