as a Schalke supporter i don´t believe this. Heiko was part of the best defence in Bundesliga last season. He´s originally a CB, but also played several times as a left back and then half of the season in midfield. To be honest, he played everything except keeper and striker.
But he just signed a new contract and with Felix Magath as new coach there is a lot of fresh hope among the Schalke players. And Magath recently rejected a 15 million Euro offer for keeper Manuel Neuer by FC Bayern, so he is not very open for offers for his top players