I'm not going to miss Rajai Davis, per se. He was alright to have around, and he provided a bit of value here and there, but in the grand scheme of things, losing Rajai Davis isn't really a big worry. He's a serviceable 4th OF, in that he can handle lefty pitching (and only lefty pitching), and is pretty good at stealing bases. He strikes out a lot, doesn't walk very much, and can be frustrating to watch defensively. As far as skillsets go, it's not all that tough to find someone who can play mediocre corner OF defense and hit lefty pitching. The speed is probably less replaceable than the other skills he provides.
I guess that kind of brings us to Moises Sierra though, doesn't it? Assuming the Jays stand pat, as far as the offense is concerned, Sierra stands to get a lot of AB's against lefty pitching, which isn't terrible, I guess? I dunno, it actually probably is-- Sierra doesn't really have a huge sample of plate appearances against lefties, but that sample doesn't paint a great picture. There's a pretty decent chance that the Sierra experiment goes poorly and that an alternative needs to be found.
From within, if Sierra just outright sucks, he can be replaced with, say, Kevin Pillar or Brent Morel, until they suck too much, or from outside the organization with someone else. Someone like Jeff Baker, who has a career .375 wOBA vs. LHP could be a nice option to platoon with Adam Lind and come off the bench otherwise. I guess Baker could even fill in as a 2B option in a pinch, even with some choppy defense. Maybe as a platoon thing, but that's another post, I suppose. He's playing mostly 1B/LF these days.
Anyway, I'm getting off topic a bit. Davis is a fast guy who hits lefties, and he probably won't be replaced in a single transaction/callup. Finding someone who can handle lefties isn't the tough thing, but finding a guy who can sit on the bench for a while and then come steal some bases or take over defensively for Jose Bautista/Melky Cabrera in the 8th inning is probably a bit more important.
I'm looking at a guy like Sam Fuld. He's nothing special, offensively, but he's pretty fast, and can offer some nice defensive value off the bench. That 9.9 career walk-rate is fairly handsome, especially off the bench, and there are some nice stolen base totals between his career and minor league numbers. He was recently non-tendered by the Rays, and shouldn't make much more than $1MM, if that.
I think the alternative is Anthony Gose. Gose sucks at hitting, but can play defense and run fairly well. He's really young, and has, for some reason, been called up for extended periods of time twice in the last two years. It would be pretty nice to get Gose a full season at AAA and maybe learn how to hit, rather than sitting him on the bench 5 days a week. Sure, he might never hit well, and will have all of his value tied in baserunning and defense, but hey.
Either way, I think the main point here is that players like Rajai Davis have a pretty good use, especially late in a ballgame, and that the Jays could probably use someone to have on speed dial. Fuld is just a personal favorite of mine, but a guy like Juan Pierre or DeWayne Wise would fill the same void. Assuming we can avoid an 8-man bullpen situation this year, there should be enough room to carry someone to run fast and do not much else.