Skacel netted a hat-trick at Tynecastle on Saturday, taking his tally to four goals in four games since last month returning to Edinburgh after a successful season-long spell four years ago ended in the 2006 Scottish Cup success.
"He's got good technical ability and he's obviously got a goal threat - that's the last four goals at Tynecastle he's scored for us," said Jefferies.
Skacel netted the opener after a minute and 14 seconds, drilling in after a strong run from Suso Santana and Kevin Kyle's lay-off, before curling in a second with a 24th-minute free-kick.
The Czech Republic midfielder then saw a shot ricochet on to the crossbar in the first half and he had to wait until the second minute of stoppage time at the end of the game for his third, when he made space for himself to tuck in a right-footed shot.
Jefferies added: "We had to wait a long time to get it but it was a great finish, especially with his right foot."
Skacel scored 17 times in his first spell with Hearts, but his third goal today was his first goal at the Gorgie End of Tynecastle.
Skacel had been asked by Hearts fans when he would score at the Gorgie End and he was pleased to put the talk at an end.
"A hat-trick is not important, but it's a nice feeling," said Skacel.
"I'm pleased and happy, but I'm more pleased I scored at the Gorgie side."
Hearts have now won two straight games, with today's success coming after last weekend's 1-0 victory at Aberdeen.
"In the end it was a very comfortable win against a stuffy side who never really gave up, they kept plugging away," said Jefferies.
The two victories have coincided with the return of captain Marius Zaliukas, who was the subject of a contract impasse which Jefferies believes is now at an end.
"I don't anticipate any problems," said the manager.
Saints had few chances of note and now have five points from nine matches this term and are still seeking their first points away from Paisley.
Michael Higdon spurned an early opportunity, Paul McGowan shot straight at Hearts goalkeeper Marian Kello and Garry Brady shot over late on in the only opportunities Saints had, leaving manager Danny Lennon frustrated.
Assistant boss Iain Jenkins faced the media and was disappointed after the Buddies suffered a fifth away loss of the season and were left with one point from a possible 18 in their last six games.
"The last couple of weeks have been sore for us," said Jenkins.
"At crucial, crucial times in the games we're losing crucial goals.
"It started from Inverness when we conceded one just before half-time and one just after half-time and it's become a little bit of a habit.
"We're conceding the worst goals at the worst possible time and to try to put the finger on that is quite hard.
"To give ourselves any chance we've got to stop these silly errors and silly mistakes as a team."