He played over 1000 games as goalkeeper for SSV Jahn Regensburg, and also for FC Bayern Munich from 1942 to 1945.

In his 38 international games,[2] Jakob kept eleven clean-sheets and while he was in goal, Germany were only defeated eight times.

[3] 'Jakl' Jakob was an all-round athlete who managed considerable results in track-and-field, winning the Bavarian hurdles race championships repeatedly, which led a decathlon promoter to almost persuade him to pursue a decathlon career.

[4] Jakob became Germany’s number one goal keeper after the 1934 World Cup, replacing Willibald Kress, who had fallen out of favour with Reich coach Otto Nerz after a momentous blunder by Kress in the semi-final had arguably cost Germany a place in the final.

In his 1978 book Fussball, Helmut Schön characterised Jakob as follows: "Thanks to his size and physical impact he was especially adept in catching high crosses and usually prevailed in turmoils inside the goal mouth."