Eye of Round...Injection Needed

My last cook was a night cook practice and all went OK.  The meat was good but did not meet my high standards.  I now know that when I cook any beef on the smoker, I am going to make damn sure I inject that puppy.  I have a picky eater in my family so I overcooked the meat a bit.  I should have pulled the meat around 145F seeing how much more cooking occurred during rest time.  The sammies were good but not "My BBQ Shack" good.  The true star of the night was the Kielbasa I smoked, going to have to make sure I get three next time.   OK so lessons learned.

Eye of Round Roast (Beef)
Char-Griller Pro Duo
Time: 3hrs (cook) 4hrs (total)
Ambient Temp: 45F-47F (Night)
Cook Temp: 225F-250F
Wood: Hickory (75%) Mesquite (25%)
Charcoal: Briquettes (50%) Lump: (50%)
Practice (1st)