Runs created are the context independent representation of every offensive number. Stolen bases, double plays hit into, total bases, sac flys, sac bunts, walks, everything. So, when Teixeira has 80 RC to Berroa's 82, your claim the offensive numbers make a case for him is incorrect. Once you consider what position the production came from, it only adds to Berroa's case.
Here is the defensive spectrum
DH - 1B - LF - RF - 3B - CF - 2B - SS - C
The further left you are on the spectrum, the easier it is to find production. Teixeira played over 75% of his games as 1B in '03, Berroa played every game as a SS. When the offensive production was marginally the same, whose contribution was more valuable when you consider position?