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Roki Sasaki, a 20-year-old right-hander who plays for Japan's Chiba Lotte Marines, pitched one of the greatest games in professional baseball history on Sunday. He notched the first perfect game in the Nippon Professional Baseball league in 28 years. He set new league records for strikeouts, both in total (19) and in a row (13). He showcased the arm strength to average nearly 100 mph on his fastball, and the grace to credit his start in part to the work of his catcher, a teenager named Kou Matsukawa.

Anytime a relative unknown to American audiences commands attention the way Sasaki did on Sunday, it's bound to stir curiosity. Who is this pitcher? What does he throw? And will he ever come to the United States, following the same path two-way phenom Shohei Ohtani and new outfield sensation Seiya Suzuki have in recent years? 

To validate that curiosity and to honor Sasaki's performance, we here at CBS Sports decided to answer nine questions about him, his game, and his future -- or, one question for each of the perfect frames he pitched during his masterful performance. 

1. Where does Sasaki's game rank historically? 

One measure of Sasaki's dominance is a Bill James invention called Game Score. The premise is simple. Pitchers begin their start with a baseline of points. Every time they do something good, like record a strikeout, their point total increases; every time they do something bad, such as give up a run, their point total decreases. At the end of their outing, they have a single number to encapsulate their work. 

Sasaki's Game Score on Sunday was 106. For reference, the highest Game Score for a nine-inning start in Major League Baseball since integration belongs to Kerry Wood's 20-strikeout performance in May of 1998. Wood surrendered a hit and plunked a batter that day, but he did not allow a run as part of his signature performance.

Wood's Game Score that day was 105, a point short of Sasaki's.

2. Is Sasaki always this good?

Sasaki may have only entered the American baseball fan's world on Sunday, but he's been pitching professionally with the Marines since last season. In 19 career outings, he's amassed a 1.78 ERA and a 6.14 strikeout-to-walk ratio. He's punched out 31.4 percent of the batters he's faced in his career. Bear in mind that NPB's hitters are not as prone to striking out as their American counterparts. NPB's league-wide K rate is 21 percent this season, as compared to the 23 percent posted by MLB hitters in 2021.

3. What are Sasaki's mechanics like?

Sasaki's delivery sees him release the ball from a three-quarters slot. Arguably the most defining aspect of his operation entails his high leg kick. He also features a wrist wrap in the early stages of his arm action, a common tic among Japanese pitchers that scouts view negatively because of its potential impact on command and health.

 4. What pitches does Sasaki throw?

On Sunday, Sasaki leaned heavily on two pieces of his arsenal: his fastball and his splitter (some sources have labeled it as a forkball, but the pitches are more alike than not). Those two accounted for 99 of his 105 pitches, good for a 94 percent usage rate. He does have other offerings at his disposal, including two breaking balls.

5. Are there any MLB comparisons for Sasaki's fastball?

In a word, no. According to data obtained by CBS Sports from Sunday's start, Sasaki's fastball averaged better than 99.5 mph and featured 19.8 inches of induced vertical break and 15.4 inches of horizontal break. That's an elite, unmatched combination.

For context, consider New York Yankees ace Gerrit Cole

Cole's fastball might be the best in the majors. Last year, it averaged 97.7 mph and featured 17.9 inches of induced vertical break and 11.9 inches of horizontal break. Among pitchers with at least 200 innings thrown last season, Cole's heater ranked in the 99th percentile in velocity; the 80th in induced vertical break; and the 95th in horizontal break. It's a fantastic pitch, and even it can't match Sasaki's numbers across the board.

The above numbers do come with some caveats. Sasaki's metrics almost certainly benefit from the differences between the American and Japanese ball. The latter is tackier, providing a better grip and negating the need for adhesive substances like pine tar or Spider Tack. Additionally, Cole's fastball features a more optimal spin axis. 

Sasaki's fastball is a monster offering all the same, and it's the instrument that should deliver him greater fame and fortune over the coming years.

6. What about Sasaki's splitter?

Finding comparisons for Sasaki's splitter (or forkball, again, depending on the source) is difficult for other reasons, as the pitch isn't as widely used as the fastball. To wit, only 29 big-league pitchers threw at least 100 of them last season. 

Sasaki's splitter checks in at 91.2 mph with 2.30 inches of induced vertical break and 7.80 inches of horizontal break. That velocity would rank as the second fastest, trailing only Hirokazu Sawamura of the Boston Red Sox. Sasaki's break numbers, meanwhile, compare most favorably to those of Blake Parker (2.9, 7.40). Parker's splitter last season generated a 36 percent whiff rate and a .232 average against.

For those wondering, Shohei Ohtani's splitter has about the same amount of induced vertical break as Sasaki's (2.40 inches), but comes in softer (88 mph) and with less run (4.90 inches). 

7. When can/will Sasaki come to MLB?

The actual question is whether or not Sasaki would even want to come over. MLB is considered the top league in the world, but NPB is a strong No. 2 and not every player has the same priorities or desires. Some individuals prefer to remain in Japan for personal or professional reasons that outweigh competing against MLB talent.

Should Sasaki decide he wants to pursue a career in North America, then he'll have to make another important decision: how much does he care about money? That's because the cruel irony of MLB's rules governing international free agents is that they deter the world's best players from joining the league as soon as possible. 

Under the current agreement, players who are younger than 25 years old (or who have fewer than six years of professional experience) are subject to the international bonus pool system that also applies to true international amateur free agents (e.g., the teenagers who sign each July 2). That policy greatly limits the signing bonus potential of these players, and explains why Shohei Ohtani signed with the Los Angeles Angels for less than the 30th pick in the draft despite being a big-league-ready phenom.

Everything is subject to change should the MLB and MLB Players Association agree to an international draft. For our sake, let's assume they don't. Sasaki would have to figure out if he wants to maximize his earnings. An affirmative answer would have him waiting to make the leap until after he celebrated his 25th birthday and accrues six years of pro experience, putting him on track to debut in the majors come 2027. Alternatively, he could request for his team to "post" him earlier than that. There is no guarantee the Marines would oblige. 

There are error bars on all of this, obviously, but the safe assumption is that Sasaki is years away from being a realistic option for big-league clubs.

8. How does the posting system work?

It goes like this. NPB teams can "submit" a player for big-league consideration. MLB clubs then have 30 days to negotiate a deal with said player. If no contract can be agreed upon, the player returns to NPB. If the player does reach terms with a MLB team, then the NPB club receives a "release fee" based on the size of the contract. Essentially, the system is in place so that big-league teams cannot raid their overseas counterparts without those teams receiving some form of compensation in return.

To use a recent example, Seiya Suzuki's contract with the Chicago Cubs is worth five years and $85 million. In accordance with the agreement between MLB and NPB, the Cubs also had to pay the Hiroshima Toyo Carp a release fee exceeding $14.6 million. 

Most of the NPB players who join the majors do so through the posting system. In order to be an exception -- and to be deemed a true international free agent -- a NPB player has to have at least nine years of professional experience. Those cases are rare, and it's highly unlikely that Sasaki will be one of them if he is to come to America.

9. What's the story with Sasaki's catcher?

As we noted in the introduction, Sasaki made a point of praising his backstop, 18-year-old Kou Matsukawa, after the fact. "I think Matsukawa called a great game behind the plate so I was able to just listen to him and make good pitches," he said.

Sunday's game marked just the seventh of Matsukawa's professional career. He won't celebrate his 19th birthday until October, and he's hitting just .167/.167/.250 in his first 26 plate appearances. None of that mattered on Sunday; all that did was how his guidance from the squat helped Sasaki immortalize them both in baseball history.