Erasmus impressed playing just behind Thamsanqa Gabuza for Bucs, particularly in the side's run to the CAF Confederation Cup final in November.
Erasmus, however, joined Ligue One outfit Stade Rennais late last month, prompting Tinkler to shift offensive midfielder Myeni up front.
"Obviously we have been playing a lot of matches in a 4-4-2 formation and truth be told, Kermit is one of the players who knows how to play in the hole," says Tinkler.
"Playing 4-4-2 you need that striker that has that ability. When we lost Kermit we needed to find someone who can do that. Sifiso was the natural choice I knew from our days at Wits.
"We were successful also back in 2012 during the Champions League with Sifiso playing that role. So he himself put up his hand and said, 'Coach, let me play behind Gabuza'.
"The last two performances have been fantastic from Sifiso," Tinkler adds.
Pirates next host Absa Premiership leaders Mamelodi Sundowns at Orlando Stadium on Wednesday.