On Friday night, Max Scherzer spun another gem with a 10-strikeout performance against the Mets in which he allowed one run over eight innings. With this outing, the remarkable has happened. Scherzer is now the No. 1 starting pitcher in Major League Baseball according to Bill James’ World’s #1 Starting Pitcher Rankings.

This isn’t the first time Scherzer has taken the top spot in the rankings, although it has been a while since his last visit there. In fact, it’s been more than a year—Clayton Kershaw has held the No. 1 ranking since July 7, 2015, when he took the spot back after Scherzer’s five-day reign. Since Kershaw first topped the leaderboard in May 2013, Scherzer is the only player to surpass him, doing so twice for a combined 40 days before Friday.

As it stands today, the two of them are stuck in a battle for the top spot, with the rest of the league trailing behind them. Here is the current top 10, while the full list can be viewed on Bill James Online.

The rankings system is based on a pitcher’s Game Score, and although it weighs recent performances more heavily than past ones, it also considers the consistency and longevity of a pitcher over extended periods of time. A full explanation of the process can be found here at Bill James Online, although the basics of it are that for each game pitched, 3 percent of a pitcher’s total is taken away and 30 percent of his Game Score from that game is added to it. This results in approximately 63 percent of a pitcher’s total score being based on the past year, with the other 37 based on what he did before then.

Although Scherzer only recently passed Kershaw, the two have been close for a while now. Kershaw started the season with a score of 564.3, with Scherzer within striking distance at 550.6. Scherzer’s Game Score of 78 on Friday was enough to propel him to the top spot after weeks of catching up, taking advantage of Kershaw’s score of 59 against the Indians in his most recent start on Tuesday to finally make the move.

Naturally, there was some disagreement when Bill tweeted on Saturday about Scherzer’s ascent. For further discussion and an explanation behind the ranking, see Bill’s post here. Based on the response to that post, he also added another one today defending his choice of 3 percent decay in his system.