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If you were using sabermetric paradigms, that wouldn't be enough, no.
If you're using tools scouting, then a single weekend can be enough to make a decision.
Stephen Strasburg doesn't need 150 IP of performance; he needs to show you he can throw strikes. Michael Pineda doesn't need a year at AA and then one at AAA; he needed those two outings in ST for me to make a decision.
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BTW, it's not "two weeks." He's 52-for-110 getting on base.