Weak(er) serendipity in Fleming's discovery?

As a serendipity engineer, I am always looking for examples of discoveries made serendipitously. The quintessential example is Alexander Fleming's stumbling upon penicillin, a discovery of monumental import to mankind. That discovery has been dissected and theorized over for more than 90 years. The story goes something like this:

"Fleming, a bit of an absent-minded professor (and a bit of a slob), left culture plates streaked with Staphylococcus on his lab bench while he went away on summer holiday. When he returned, he found that “a mould” had contaminated one of his plates, probably having floated in from an open window. Before discarding the plate, he noticed that, within a “ring of death” around the mold, the bacteria had disappeared. Something in the “mould juice” had killed the staphylococci." (link)

As this wonderful article by Kevin Blake, PhD in Asimov Press shows, the official and beautiful story is unlikely to be true. In particular, the contamination could not have happened after the beginning of the culture, something Fleming did not know at the time. A more likely scenario is one where Fleming was looking for antibacterial lysozymes and instead stumbled upon another type of antibacterial product altogether, but in this scenario his goal was to find a way to kill bacterial pathogens, not just simply cultivate them.

The truth is still unknown, but whatever it is, Fleming did have a prepared mind and did recognize an unexpected pattern that required further exploration. It is just that the nature of chance may very different depending on the scenario: the size of the leap defines the strength of serendipity. Fleming's has to be downgraded.