If I have a job offer in Financial Analytics from Germany eligible for Blue Card, but my recognized degree is Mechanical Engineering, would that cause any problem as an unrelated educational qualification? (my highest degree is PGDM from India which is unrecognized and I have 6 years experience in Financial Analytics)
However, in practice they're lenient towards it. I had almost the same issue and was highlighted by the person who took my interview at the embassy for the National visa that I may not get the Blue card. But when I went for the blue card appointment, they gave me a Blue card. My employment was in Sofware engineering, and there was computer science in one of my graduation courses as minor. I have MBA in finance though.
At the worst, you'll get normal residence permit (Aufenthaltserlaubnis), instead of Blue Card which as far as I know differs mostly if you're married and want to bring your partner with you. But don't take my word and read here and here about all the differences.
Yes, the job you are applying for must correspond to the degree you have (i.e. they must match)
Otherwise you must apply for a normal work visa and based on your qualifications (practical experience), then a determination will be maded if this conforms to a highly qualified employment that is needed.
1) A foreigner shall be granted an EU Blue Card pursuant to Council Directive 2009/50/EC of 25 May 2009 on the conditions of entry and residence of third-country nationals for the purpose of highly qualified employment (OJ L 155,18.6.2009, p. 17) for the purpose of employment commensurate with his qualification, if
a) holds a German or a foreign higher education qualification which is recognised or otherwise comparable to a German higher education qualification or
the degree must match the employment.