Why did Avner take Ish Boshes to make him king? He knew that Shmuel anointed David!
Rashi (like Rabanan, Bereishis Rabah 82:4): He expounded "Melachim me'Chalatzecha Yetzei'u" (Bereishis 35:11). This hints that [at least] two kings will descend from Binyamin, the only son of Yakov not yet born when Hashem told him this.
Why did he take Ish Boshes to Machanayim?
Radak: He wanted to anoint him first over Ever ha'Yarden, for two and a half tribes are there. Machanayim in on the border between Gad and [Chetzi] Menasheh.
Malbim: He wanted to anoint him first over Gil'ad, for Anshei Yavesh Gil'ad loved Sha'ul.
QUESTIONS ON RASHI
Rashi writes that Avner expounded that another king must descend from Binyamin. If so, why was he punished for making Ish Boshes king, and delaying David's kingship (Sanhedrin 20a)?
Riva (Bereishis 35:11): He was punished for his intent to embarrass David. 1
Perhaps this is because David publicly rebuked Avner. Refer to Shmuel I, 26:14:1:2. (PF)
