Heynckes will return to Bayern transformed

Genial and avuncular rather than frosty and stern: Jupp Heynckes is almost unrecognisable from the coach who led FC Bayern München to back-to-back titles in 1989 and 1990.

The 65-year-old Bayer 04 Leverkusen boss has agreed to return to Bayern in the summer to replace the outgoing Louis van Gaal, with the German titleholders knowing exactly what they are getting in most respects. Except that the man who scored 220 goals in 369 Bundesliga games for VfL Borussia Mönchengladbach and Hannover 96 has mellowed with age.

A famous German television clip from 1989 sums up the old Heynckes: sat silently between 1. FC Köln coach Christoph Daum and Bayern general manger Uli Hoeness, the red-faced coach is so tense he can barely speak. The way his cheeks flushed under pressure prompted fans to nickname him 'Osram' after a popular brand of lightbulb.

Ewald Lienen, who played under Heynckes during his first coaching spell at Mönchengladbach in the 1980s, remembers the image. "There were times when I wanted to shoot him to the moon," he said. "He put himself under such crazy pressure and when he was disappointed with us, he could be cruel and hurtful." Young players, they say, were terrified of him.

An unsuccessful stint at Eintracht Frankfurt in 1994/95, when the trainer fell out with some top players – "morals and responsibility have fallen by the wayside," he snapped – enhanced the martinet reputation. Yet after winning the 1998 UEFA Champions League with Real Madrid CF, there were signs that Heynckes was cooling down.

In 2003, he said: "These days I show more interest in the human aspect – that's what I learned in Spain." Former Germany goalkeeper Bodo Illgner, who worked under Heynckes at Madrid, added: "Jupp is the same kind of a coach as Vicente del Bosque. Quiet, businesslike, he does not reign with an iron fist like Fabio Capello or José Mourinho."

He may have been calmer, but Heynckes looked out of touch in the mid-2000s, and following unsuccessful tenures at FC Schalke 04 (2003-04) and Mönchengladbach (2006-07) it came as a shock when he took over from Jürgen Klinsmann at Bayern towards the end of the 2008/09 campaign. Hoeness, at the time, said his sacking in 1991 had been his "biggest mistake".

However, having secured Bayern's return to the UEFA Champions League that season, the veteran has earned more praise during his two terms at Leverkusen. His team currently sit second in the Bundesliga behind Borussia Dortmund. Former BayArena general manager Reiner Calmund said Heynckes had made "great strides" and had become "a lot more relaxed and authoritative". Few in Germany would disagree.

Heynckes himself said the change coincided with his wife being seriously ill a few years ago. "I witnessed a two-year illness involving several operations," he recalled. "During that period I reflected on everything and it became clear to me that many things in life aren't that important.

"I am not all sunshine, any more than Felix Magath is," he added. "The most important thing is to be genuine. My CV might intimidate young players, but it is important that right from the beginning I approach them and show them they can talk to me. You need to realise when someone needs a sympathetic ear."

Such words coming from Heynckes would have seemed implausible 20 years ago. However, Bayern chairman Karl-Heinz Rummenigge likes his style. "If he stands in front of you and speaks, then you know the fire is still burning inside him," he said. "He seems a lot younger than his age."