Xabi had offers from Bayern Munich and Liverpool, but announced on Friday he is staying with Bayer next season.
Merson told Sky Sports: "I am in shock. I can understand that you're probably happy with what he's doing, he's getting better. He has praise and rightly so, but these clubs appear once... I just hope he doesn't regret it. I know what management is like, in the end everyone gets fired.
Advertisement
Advertisement
They are two of the most important jobs in the world of football.
You have to make money while the sun shines, and we are talking about two of the most important benches in world football (Liverpool and Bayern). They may never come again, trains don't run twice.
"I don't see Bayer Leverkusen winning the league again next year, I think the giant Bayern will be back where it has been for the last 10 years."