Raising Aces: Jake Arrieta vs. Gerrit Cole

We were treated with an enticing matchup for the AL Wild Card game, but that was kid stuff compared to this. These two NL Central clubs know each other quite well, having matched up 19 times this season, but this will be the first time in 2015 that we get to see the specific matchup of Jake Arrieta versus Gerrit Cole.

The Stats

Arrieta

Arrieta is on an epic run that might earn him the Cy Young, but individual achievements pale in comparison to the postseason aspirations of a Cubs franchise that hasn't won the World Series since 1908. Arrieta has been virtually unhittable over the past two months, with a 0.41 ERA and an opponents' batting line of .136/.182/.172 over his last 12 starts, covering 88 innings during which he has allowed just one home run.

Season Stats

• GS	IP	ERA	H%	HR%	BB%	K%
  33	229.0	1.77	17.2%	1.2%	5.5%	27.1%

Aside from an ERA flown in from the Deadball Era, Arrieta has posted rates that are strikingly similar to those of his 2014 campaign, but with about 75 more innings of work. Last season, he had a 27.3 percent K rate, an incredulously low 0.8 percent homer rate, and a 6.7 percent walk rate that had been a career-best up to that point. This year, he has allowed a league-low 5.9 hits and 0.4 homers per nine, and his longball rate trailed only Gio Gonzalez and Tyson Ross. Arrieta's strikeout frequency was the eighth highest in the game among qualified starters.

He has faced the Pirates five times this season and has dominated them, with a 0.75 ERA and 33 strikeouts to 24 baserunners. He last took on the Pirates on September 27th, allowing just one hit and no walks (he did hit a batter) while striking out nine over seven shutout frames. He also flexed his muscles at the plate, going opposite field on an A.J. Burnett fastball for his second home run of the season.

Cole

Cole had the breakout season that many were projecting prior to 2014, shaving more than a full run off of his ERA (his 2.60 mark ranked fifth in the National League) while trimming the free passes back down below 2013 levels. He also cemented his place as the ace of the Bucs rotation, taking the mound 32 times and throwing 70 more innings than he had in any previous season.

Season Stats

• GS	IP	ERA	H%	HR%	BB%	K%
  32	208.0	2.60	22.0%	1.3%	5.3%	24.3%

Cole set career-bests in every single category on the above table, yet aside from the innings, the numbers were within spitting distance of previous marks. The K rate was just 0.1 percentage point better than last season, the hit rate just 0.2 percentage points better. The biggest leap was made in the walks department, as he walked four more batters in 70 more innings.

He hasn't quite matched Arrieta's run prevention when these teams go head to head, but still boasts a 2.13 ERA in his four starts against the Cubs this season. He has just four walks against a Cubs team that runs a lot of deep counts.

The Stuff

Arrieta

Pitch Type	Count	Freq	Velo (mph)	pfx HMov (in.)	pfx VMov (in.)	H. Rel (ft.)	V. Rel (ft.)
Fourseam	256	7.74%	95.02	-3.48	9.05	-3.19	6.46
Sinker	1418	42.87%	95.33	-7.26	7.58	-3.23	6.44
Change	150	4.53%	89.71	-9.44	2.45	-3.62	6.22
Slider	947	28.63%	90.87	3.30	2.84	-3.38	6.34
Curve	515	15.57%	81.31	6.29	-8.95	-3.22	6.42
Cutter	22	0.67%	90.18	4.14	2.09	-3.39	6.42

Arrieta brings an elusive pitch mix to the table, starting with a fastball that averages 95 mph and that he can pinpoint in any quadrant of the strike zone. He brings the heat on half his offerings, and though the changeup only makes an appearance in favorable counts against left-handers, he has two sharp breaking pitches to make the arsenal truly devastating. He'll use either breaker or the fastball to get strikeouts, whiffing 63 or more batters on each of the three pitch types this season. The movement on the slider is wicked, with very late break that carries fastball-like deception for much of its flight path. The pitch carves a two-plane slice as it approaches the strike zone. The curve is a steeper pitch with a larger vertical component to its break and less lateral movement, and the pair of breaking balls give Arrieta multiple options to exploit effective velocity and attack batter vulnerabilities.

Cole

Pitch Type	Count	Freq	Velo (mph)	pfx HMov (in.)	pfx VMov (in.)	H. Rel (ft.)	V. Rel (ft.)
Fourseam	1596	51.01%	96.55	-6.97	7.76	-2.57	5.75
Sinker	507	16.20%	96.20	-8.91	5.52	-2.58	5.69
Change	115	3.68%	89.02	-7.90	4.78	-2.61	5.60
Slider	666	21.28%	87.74	2.96	-0.41	-2.68	5.60
Curve	244	7.80%	82.22	8.44	-3.48	-2.49	5.61

Cole throws hard. His average velocity on the four-seam fastball is the eighth highest in baseball this season, just behind the 96.6 mph average of Matt Harvey. The changeup has been diminishing in frequency over the past few seasons, and in 2015 Cole traded half of his curveballs for sliders, effectively limiting the scope of his pitch repertoire but maximizing his greatest strengths. He can get vicious arm-side run when he goes to the sinker and he does so without sacrificing any velocity, giving batters fits of struggles with tracking as well as timing. He reels back the fastballs a tad as he gets deep in the count, bringing more sliders to the plate instead, but no matter the count Cole brings the heat at least 45 percent of the time. The simplified approach may have also helped peripherally with his pitch command, given that Cole was repeating the fine-grained elements of his delivery with greater frequency.

The Mechanics

Arrieta

Mechanics Report Card

• Balance	55
  Momentum	55
  Torque	50
  Posture	60
  Repetition	65
  Overall	B

For an explanation on the grading system for pitching mechanics, please consult this pair of articles.

When Arrieta broke out last season, there were mechanical underpinnings that helped to solidify the legitimacy of his improvement. Specifically, he ironed out the lift and stride portions of his motion, trading the inconsistent timing patterns of his past – sometimes he would stop at the top, other times not, and the mid-delivery pause would change in duration from pitch-to-pitch – for a smooth increase of momentum throughout the delivery. He was able to repeat with much greater frequency compared to the overcomplicated pace of his past. This season has been more of the same, which is a relief given the volatility inherent in pitchers and their tendency to morph from one season to the next. The improved momentum was not only easier for Arrieta to repeat, but the extra charge toward the plate effectively lengthens his stride to give him a deeper release point.

He strides closed, such that his front foot lands to the third-base side of the centerline, but he lines up the gears with this approach, as it appears to be consistent with his personal signature. There are still some inefficiencies with his stability, specifically a lean-back toward second base during the stride phase that throws a wrench into his balance in the Z-plane. But he receives above-average marks (flashing plus) in the balance department by maintaining a better head position in the lateral and vertical dimensions. The posture is very strong despite a relatively high arm slot, as the high angle of shoulder abduction allows Arrieta to find a tall release point without sacrificing posture to get there.

Cole

Mechanics Report Card

• Balance	65
  Momentum	50
  Torque	70
  Posture	60
  Repetition	65
  Overall	A-

Cole's delivery gets better with each passing season. He used to have a slow pace to the plate that resulting in a momentum grade of 40, but he has since altered his stride pattern in order to get more out of his delivery. The momentum still starts slowly, leading with the hip and moving forward directly from first movement. But the biggest improvements have involved a sudden gear-change after lift, giving him a late burst of kinetic energy to add length and power to his delivery. Many pitchers would struggle to harness such an abrupt approach, but Cole has continued to improve in this area and has demonstrated the learning curve to adapt quickly.

Cole invokes massive torque that relies on timing of trunk rotation to let his powerful hips create separation after foot strike. The style with minimal upper-body load but a heavy delay of trunk rotation invokes comparisons to Roger Clemens, a comp that holds firm when looking at the massive degree of delay before pulling the trigger, as well as the high-end velocities that can result from size and technique. The balance is incredibly strong in all three planes, and he maintains his head over the center-of-mass even as the arm comes through during the high-speed phases of rotation, giving Cole a rare blend of stability and power in his delivery, and he earns the “A-” on his report card with three different attributes that grade out as a 65 or better for his mechanics.