What AL team had the most pitching WAR, according to FanGraphs, in 2016? This isn’t much a trivia question, really, since you’ve almost certainly heard it already, and if you haven’t, the title and topic of this article should make the answer obvious. That’s right it was the Blue Jays Astros, with 20.1 fWAR. But just behind them: the Blue Jays, with 19.2 fWAR, and an AL-leading 3.79 ERA.

Now, that ERA masked some flaws: the Jays had the fourth-best FIP in the AL, and their K and BB numbers indicate they probably benefited from some soft contact and lucky bounces. Nor did they seem to do that much to promote easy contact; while they had an above-average 46.6% ground ball rate, Baseball Prospectus’s DRA, the current best publicly available attempt at accounting for skills like contact management, put the Jays at a pedestrian 4.19, seventh in the AL.

But what was notable about the Jays rotation last year was not their performance, or not alone. What was notable was their performance as compared to preseason expectations. For each of the Toronto starting five — Marcus Stroman, J.A. Happ, Aaron Sanchez, Marco Estrada, and R.A. Dickey — here’s the average of their projected performance from Steamer and ZiPS, and how they actually performed:

2016 Blue Jays Rotation: projections vs. performance IP K/9 BB/9 HR/9 ERA FIP WAR IP K/9 BB/9 HR/9 ERA FIP WAR R.A. Dickey Projection 189 6.07 2.89 1.24 4.31 4.72 1.1 R.A. Dickey Actual 170 6.68 3.34 1.49 4.46 5.03 1.0 Marcus Stroman Projection 149 7.57 2.27 0.92 3.72 3.62 2.7 Marcus Stroman Actual 204 7.32 2.38 0.93 4.37 3.71 3.6 Marco Estrada Projection 161 6.89 2.69 1.48 4.23 4.72 0.9 Marco Estrada Actual 176 8.44 3.32 1.18 3.48 4.15 3.0 J.A. Happ Projection 141 7.60 2.82 1.18 4.13 4.14 1.7 J.A. Happ Actual 195 7.52 2.77 1.02 3.18 3.96 3.2 Aaron Sanchez Projection 122 6.74 4.40 0.85 4.17 4.42 0.8 Aaron Sanchez Actual 192 7.55 2.95 0.70 3.00 3.55 3.9 AVERAGE DIFFERENCE 35 0.53 -0.06 -0.07 -0.41 -0.24 1.5 AVERAGE DIFFERENCE (NO DICKEY) 49 0.51 -0.19 -0.15 -0.56 -0.38 1.9

Note: I left out PECOTA from the projection average because DRA measures something subtly different from FIP and ERA — pitcher performance without (among other things) catcher framing — and that’s an important distinction, for reasons we’ll get to later.

Almost across the board, each of Toronto’s pitchers beat out their projections by a substantial amount. There are a lot of reasons for that, depending on the pitcher, and almost all of them are outside the scope of this article. Stroman took a bit of a step back on a per-inning basis, but he was healthy and pitched a full season for the first time in his big-league career. Sanchez also added a huge number of innings, as all the projection systems expected him to spend some time in relief; he improved in each category as well, despite the more challenging role he occupied.

There’s a similar storyline like that for nearly each pitcher, with the possible exception of Dickey, who had a characteristically mixed season. Dickey, of course, is the only pitcher of 2016’s rotation who won’t be returning to the Jays for 2017, having signed with the Braves. When you remove him from the picture, the Jays were even more of a surprise last year.

That suggests some reasons for optimism when it comes to 2017, as the Jays get a possibly resurgent Francisco Liriano for a full season in addition to the four non-Dickey starters from the beginning of 2016.

But the 2017 projections that are currently available don’t reflect that entirely. Steamer thinks every one of Sanchez, Stroman, Happ, and Estrada will take a step back, losing 0.9, 0.4, 0.8, and 1.5 WAR, respectively. And while ZiPS is more optimistic in some respects — chiefly, in that it thinks Sanchez will add 0.7 WAR — it also sees declines in store for Stroman (-1.4 WAR) and Happ (-0.7). (It projects Estrada to match his 2016 WAR almost exactly.)

The result is a Toronto rotation that is projected to be good, but not great, a developing theme for the 2017 Jays. The FanGraphs depth charts currently has the starters pegged for 13.0 WAR, ninth in the AL and firmly in the middle of the pack.

The rotation’s overperformance in 2016, however, lays out a blueprint for how they could repeat in 2017. As Mark Davidson described in the above article on Liriano’s second half, the Blue Jays have a heckuva catcher helping out their pitching staff in Russell Martin. You almost certainly know about his framing abilities — worth 14.2 runs in 2016, per Baseball Prospectus, fifth in MLB — but while game calling is harder to quantify, Mark made a pretty compelling case that Martin worked with Liriano to develop a different kind of game plan upon his return to Toronto, and that it was a major contributor to Liriano’s second-half success.

That’s why I’ve been studiously not discussing Baseball Prospectus’s view of the Jays rotation, both before 2016 and after, but it’s another powerful argument for optimism.

2016 Blue Jays Rotation: BP projections v. performance IP BB/9 K/9 HR/9 DRA WARP IP BB/9 K/9 HR/9 DRA WARP J.A. Happ Projected 165 2.9 7.3 1.1 4.43 1.2 J.A. Happ Actual 195 2.8 7.5 1.0 4.42 2.1 Marco Estrada Projected 165 2.9 6.7 1.3 4.74 0.6 Marco Estrada Actual 176 3.3 8.4 1.2 4.40 1.9 Aaron Sanchez Projected 82 4.2 6.5 1.0 4.80 0.2 Aaron Sanchez Actual 192 3.0 7.5 0.7 3.77 3.5 Marcus Stroman Projected 164 2.6 7.4 1.0 4.06 1.9 Marcus Stroman Actual 204 2.4 7.3 0.9 3.43 4.5 AVERAGE DIFFERENCE 48 -0.3 0.7 -0.2 -0.50 2.0

Even BP, which does the best it can to totally isolate the pitcher’s performance from the other players on the field, thinks the Jays starters were better than expected last year. I expect that PECOTA (when it’s released) also won’t buy that all four of these pitchers have made a permanent leap forward. But it’s not unreasonable to think that some of them really did make a fundamental change last season, and that their projections have some unrecognized upside.

The Blue Jays’ success in 2016 had a lot to due with the simultaneous progress four of their five pitchers made, and all four of those pitchers are coming back for 2017. Projection systems are, by design, slow to react, and they aren’t convinced that any of those leaps are permanent. But even if only some of them are, the Blue Jays are well set up to be a surprising success in 2017, too.