I have no idea what to expect out of Juan Rivera this year. I doubt the Jays do either. I am sure he wasn't a player that Alex particularly wanted, just someone he had to take to make the Vernon Wells trade.
Juan didn't have a good year last year:
Nor did he have good defensive numbers. Fangraphs had him at a -6.4 UZR/150. He doesn't have a lot of range, has an ok arm, makes the odd error.
There are a few good signs though. He had a .261 BABIP, down from a career .283 mark. He also hit much better on the road (.283/.336/.483) than at home (.223/.289/.336). Right handed power hitters did very well at Rogers Centre last year, maybe it will help him out too. He hit better in the second half of last season (.272/.333/.407) than he did in the first half (.240/.299/.409).
His career numbers at Rogers Centre aren't good (.190/.188/.349) but that is only in 63 at bats so means little.
He is in the last year of his contract so maybe there will be a kick to get another one.
Bill James figured him to hit .270/.324/.444 with 15 homers in 409 at bats. That would have been before the trade.
Me? No idea. Let's say .275/.335/.450 with 20 home runs in 500 at bats.