On the other hand, having done the hard work four days ago by triumphing in the first leg in Zagreb, Croatia finished the job comfortably against a much-improved Greek team, who were full of attacking intent and tenacious tackling.
"But we know on the other side that management is such a hard job. If we had won 1-0 (in the first leg), it would have been very hard tonight", said Croatia coach Zlatko Dalic, who took over from the sacked Ante Cacic only last month.
The Swiss qualified 1-0 on aggregate, the tie ultimately being decided by the hugely controversial penalty converted by Ricardo Rodriguez in the first leg in Belfast on Thursday.
For the first 30 minutes Greece were in control.
Speaking to the BBC, Boyd said: "I think Michael O'Neill has done a fantastic job with Northern Ireland".
"Our performance and reaction tonight was fabulous".
I do, however, share in the frustration of seeing a poor refereeing decision at Windsor Park rob Northern Ireland of a place in the World Cup finals.
Chris Brunt brought a good save from Sommer with a swerving long-range strike in only the third minute, before Stuart Dallas fired over from the resulting corner.In a high-tempo opening to the game, Haris Seferovic should have doubled the hosts' aggregate lead but headed Xherdan Shaqiri's vicious cross past the far post.
The Northern Ireland boss has remained tight-lipped on his future following the country's World Cup qualifying failure.
The lure of replacing Strachan and returning Scotland to a major European competition could also prove tempting but there are concerns that O'Neill's rising reputation may have put him out of their price range.
After three years in charge of Irish side Rovers, O'Neill was appointed as Northern Ireland manager.
They were again indebted to Rodriguez on Sunday when he cleared a goalbound header from Jonny Evans off the line in stoppage time as Northern Ireland pressed for an equaliser.
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