The table below shows the discrepancies between Yahoo and Baseball Reference
It seem like SLGA is supposed to be slugging percentage allowed. Yahoo may have divided TB by TBF instead of AB. Buehrle has allowed 4011 TB in his career and 4011/10317 = .389. But if they used that for SLGA, what is OBSA? I thought it might be OPS allowed, but then Buehrle should have .704 using Yahoo's numbers. But they show only .689. So it is not clear what is going on.
Here are the links the Yahoo pages for these three pitchers.
Now for Baseball Reference