Like you said, Tillman and Gausman should be above average but then they are basically hoping the rest of whatever 3 they use can put up a 4.5 ERA or less.
The Sox are in a better position. Price is an ace (lol at you calling Wright their only good starter!) and Wright looks good too. You could do worse than Porcello as the #3. Rodriguez can probably be fine on the backend (our #5 is Dickey and he's better for what it's worth) but then they don't have anything. They'll probably make a trade.
Happ and Dickey are probably backend guys but they should be pretty decent as the #4 and #5. They are definitely better than the O's or Sox's #4 and 5. Estrada looks like a stud, might be better than anyone but Price for AL East contenders. Stroman should improve and Sanchez while he lasts has been a stud. Hutch coming in for Sanchez will be some dropoff but he he'd probably be the O's #3 SP and the Sox's #4 SP.
We are definitely in a better position than those teams as far as the rotation goes. With the lineup turning around and a very manageable schedule to close out the first half of the season it's looking like the Jays should be in AL East contention the rest of the way.