First, let's look at his velocity breakdown chart, this one sorted from pitch 1 to pitch 86:
Otani reached his peak velocity about midway through his outing, and wasn't throwing as hard at the end of the game as he was at the start of the game. This could be because of how his pitch schedule at the start of the season was off because the Fighters wanted to use him as a position player. His arm strength may not be all the way built up.
Here were his pitches according to my classifications:
50 Fastballs: 93.32 MPH, 25 in the strike zone, Middle High and Glove Side and Low the most common locations (10 each)
8 Two-Seamers: 91.63 MPH, 5 in the strike zone, Glove Side Middle, Arm Side High, Arm Side Middle all had two locations.
6 Sinkers: 94.86 MPH, 1 in the strike zone, Glove Side and Low the most common location.
18 Sliders: 79.29 MPH, 6 in the strike zone, Glove Side and Low the most common location.
2 curves: 63.24 MPH, 0 in the strike zone, Glove Side and Low and Arm Side and Low.
1 change: 80.6 MPH, not in the strike zone, Glove Side and Low.
This is how the Yahoo data broke up his pitches, in case you were wondering:
19 sliders: 79.36 MPH
65 Fastballs: 93.25 MPH
2 Curves: 63.24 MPH
The first thing I notice is that the slider velocity doesn't match the fastball velocity. Otani's slider was the slider that breaks just vertically, like a lot of sliders you see in Japan, often called something like a baby slider. It doesn't look like a hard curve, but it would make more sense when comparing velocities that he has a hard curve and slow curve. When you look at starters in the Pitch F/X era that have an average fastball of 93-94 MPH, Daniel Cabrera had the slowest slider at 81.4 MPH. Two of those pitchers even have curves over 80 MPH on average. Otani's slow curve acts somewhat like an eephus pitch, similar in velocity to Paul Maholm's eephus. The lack of a changeup is something that I think MLB teams will look at and consider when scouting Otani, as none of the qualified starters in the Pitch F/X era that threw 93-94 MPH on their fastball didn't have a changeup. I counted one, a slider/curve (according to Yahoo) against a lefty that dropped differently. Whether he threw one or none in the start doesn't really matter, it is something I think he really needs to develop to get out lefties. Anecdotally, it seemed that he got really fastball heavy when he faced lefties. It is nearly impossible to make MLB comparisons because of how his slider acted and his lack of changeup or some kind of cutter (his fastball has a lot of movement, but it is usually arm side tail, breaking back like 2-seamers).
Overall, Otani threw pitches in the strike zone 43 percent of the time. In the Pitch F/X era, only 5 out of the 201 qualified pitchers have a lower zone percentage than that. Strangely, only Francisco Liriano is extremely wild out of them, and he is the only one that you can really call a hard thrower (Gee, Hellickson, Lowe, and Vogelsong being the other four). A low zone percentage doesn't mean you can't succeed, as Hiroki Kuroda has only thrown 43.5 percent of pitches in the strike zone in the Majors, and the highest zone percentage pitchers seem to be less successful. Throwing strikes, can, at times, be overrated. The important thing is to miss bats. Here is Otani's approximate strike zone for the game in a really simple zone chart (catcher's perspective, I am not sure why it is stretching weirdly, and didn't keep my format to show the actual strike zone, which is the middle three rows and columns):
His favorite zones were low and away and throwing it high and arm side. Anecdotally, most of the high and arm side pitches were mistakes where he didn't finish his delivery. Perhaps one way to get out lefties, especially lefties in Japan, who don't face a lot of elite velocity pitchers, is to throw hard fastballs inside on them. It would seem that it would be better for Otani to throw those fastballs high and in to them get them out, rather than low, and then go low and away with the 2-seamer, something he didn't do very much. I found it interesting that both slow curves he used were against Iwamura and Milledge, two former MLBers. He threw a lot of fastballs to both of them, but focused on keeping the ball away from them.
A big thanks to Kazuto Yamazaki (@Lablynne) for pointing out the videos on YouTube, Patrick Newman (@NPBTracker) for helping me with the Yahoo data, and @YakyunightOwl as well.