Jimmys 2017, whether you want to call it a breakout or an outlier or both is perhaps better evaluated when you also consider 2016 as one. Not that he was as good in 2013-2015 as in 2017, but he was a lot better than in 2016. Looking at plate discipline stats is interesting; he had a SwStrk % of 9-10 in those years, that then dropped to 7% in 2016 before 11% in 2017.. Batters stopped swinging as often on pitches (Mainly outside the zone) in 2016, but started making more contact. Jimmy threw more strikes in 2016, but had a lower first strike %. He threw more sinkers and fewer curveballs. The stats can tell a story here. Falling behind more often (Lower first strike %) results in more of the latter pitches being thrown in the zone, and in counts where you expect to see strikes/fastballs. Fewer breaking balls means fewer swings and misses, both outside and inside the zone. So without throwing fewer strikes, you still see the BB% rise and thus K% drop even more than K/9 does. Now without looking at heatmaps and such it's harder to tell the details, like which pitches got the swings (and contact) outside the zone (My guess would be sinker), or if there was a particular pitch he was struggling to throw for strikes. The pitch value would suggest that it was the sinker. Now I didn't watch much of Jimmy in 2016, but just from the above numbers it made me think that he struggled vs RHB in 2016, and he in fact did (.802 OPS vs .685 for his career. vs LHB he was exactly in line with his career numbers) simply because sinkers that miss their spot vs a same-handed batter are just the kind of pitch you'd see more contact made against even outside the zone. Anyway, what changed in 2017 was the pitch mix, back to something very close to 2015 with more curves and fewer sinkers. What stuck from 2016 was the higher zone % compared to before, while the other numbers aren't much different from 2013-2015 with the exception of getting a few more swings, but most importantly getting more swings and misses outside the zone. Better breaking stuff, and more pitches thrown in the zone. You see the evolution where Jimmy in 2015 threw fewer fastballs and more breaking stuff, which saw more swing and miss but more walks. 2016 where where more fastballs (Sinkers) again, more strikes but more walks probably due to lacking an out pitch and nibbling more (I can't find pitches / PA, but I'd expect a spike there). 2017 going back to what showed promise in 2015 with the curveball, but this time seeing better results. Maybe because of the new curveball grip that I recall hearing about, maybe because the fastball/sinker got better. Maybe because he set himself up to throw them in the right count better. Anyway, I hadn't really looked at these stats before, but found it pretty interesting that you could tell a tale just from looking at some stats. Some of it aligns with what I remember (Like the very effective curveball in 2017), some I have no idea if they're true. But I'd say that 2016 makes 2017 look like more of an outlier than it was. 2013-2015 Jimmy was a league-average pitcher lacking some ability to finish off hitters. Add some strikeouts to that and you've got a breakout.