Poor Picked-On Uncle Eisav?
This is one of those pieces that you must read through to the end; to stop in the middle will leave you with a very wrong impression. So either stop now, or commit yourself to all of it.

The Torah tells us that while Yaakov was cooking a lentil dish, a very tired Eisav returned from the field. Eisav was obviously hungry as well as tired and asked Yaakov for some of the "red stuff" he was making. Yaakov asked Eisav to sell him his birthright, which Eisav did. 

The Gemara (Bava Batra 16b) tells us that the above episode occurred on the day that Avraham Avinu died, and Yaakov was preparing the mourner's first meal for his father Yitzchak. It then adds in the name of Rabbi Yochanan, that on that very same day, Eisav sinned five great sins - including murder and rape (not having manifest his wickedness during Avraham's lifetime). To "support" this statement, the Gemara draws on p'sukim from Tanach that indicate that the words AYEIF (tired) and SADEH (field) have connotations and associations with murder and rape respectively.

Why did our Sages pick on dear Uncle Eisav so much? Could it not have been that he just came home from the field and that he was tired? When the Torah says that Yitzchak loved Eisav because he provided food for him, why do the commentaries make the play on words on TZAYID and say that Eisav would trick his father into thinking that he (Eisav) was good and sincere?

Why, if the text of the Torah seem to say that Eisav was the innocent victim of Yaakov's opportunism and deceipt, does our Tradition call Eisav the Wicked? 

This is the place NOT to stop. Even if you are tired, keep reading. Please...
The answer begins with part of the question. The written text is not the whole Torah. There is an inseparable part of the Torah known as the Oral Tradition, which is no less sacred, no less Torah, than the Written Word.

Rabbi Yochanan did not decide that Eisav committed a murder and a rape on the day in question. Those were (Oral) Torah facts. The most Rabbi Yochanan did was to make the textual links to support the Oral Tradition. Or maybe he was just teaching us those links that were part of that Tradition. 
Just as halachic issues sometimes are understood differently from the plain text (e.g. eye for an eye, goat in its mother's milk, neither of which are taken as written), so too is it sometimes with the narrative portions of the Torah. How are we to know when a field is a field and when it has a sinister connotation? How are we to know when YOM is a 24-hour day and when it is daytime? Emunat Chachamim. Faith and confidence in the Chain of Tradition.