Short answer
to withdraw from a situation or to quit participating in a project or task, etc., and to thereby cause a negative consequence for someone.
Longer answer
We often use verbs (including phrasal verbs which this could be considered) followed by "on" to add a meaning something like "blamefully causing a negative consequence for someone or something."
For example, "She went crazy on me." Would generally mean that I was depending on her company or assistance with something, so her going crazy caused me some problem or distress.
To pull out means to depart (especially by vehicle, which I assume comes from carriages or coaches being pulled by horses, for example) or to withdraw:
pull out
- To leave or depart: The train pulls out at noon.
- To withdraw, as from a situation or commitment: After the crash, many Wall Street investors pulled out.
Since the first definition means a vehicle leaving, it would not normally be followed by on unless it meant on time or on a surface: The car pulled out on/onto the dusty road.
We can guess that it's more likely you ask about pull out on with respect to definition 2, because the three words seem to go together and in a way such that the meaning would be less obvious to many English learners.
So, to pull out on someone in this sense likely means to withdraw from a situation or to quit a project or task, etc., and to thereby cause a negative consequence for someone.
Examples:
She promised to invest $2 million in our company. We spent weeks preparing plans and drafting legal agreements in preparation for that. Then she pulled out on us at the last minute. We were so disappointed.
They were engaged for three years. Then John pulled out on her on the wedding day. He just left town without telling anyone.
He promised to help me move all of my things to my new apartment, but then he called and pulled out on me, saying he was too tired from work.
They are indicating that it was a victory that was only won through Hard work that if the team didn't work as hard as they did it may not have turned out so well. Imagine sculpting a sculpture as the goal, the team had to etch out their victory to be successful.
Best Answer
As a sports fan, I have heard this expression used many times for as long as I can remember. Instinctively, I know what it means:
That's why this phrase is commonly found in news stories such as:
Yet you have astutely observed that other writers seem to use "pull off" to mean the same thing.
However, when I scoured the dictionaries for a definition corroborating this definition, I can't seem to find one.
I did find this on a language forum:
Also, this Ngram shows that both expressions are used. I also wonder if this is an Americanism, as I didn't see any hits on the Ngram when I changed the corpus to British English. Lastly, these expressions seem relatively new (very few hits prior to 1970), so maybe the dictionaries simply have some catching up to do.
One possible origin might be the aviation phrase "pull out of a nosedive", which might explain why the expression seems to get used a lot when the ultimate victor was trailing early in the contest.