I'm no doctor (well, not that kind any way), so forgive the ignorance, but if it is not a big deal, why did Svech get shut down?
ACL injuries (and other tendon and ligament injuries) come in different grades- Grade 1 is overstretched and maybe fiber separation but no outright tear, rest and rehab only. Grade 2 is a partial tear, which can be healed with rest and rehab, but can be sped along with surgery if bad enough, Grade 3 is a total break. Torn in two pieces, surgery required.
And even within Grades 1 and 2, those, there's a lot of difference in severity. Half millimeter tear is a grade 2, but it's also a grade 2 when there's only half a millimeter hanging on.
If Pesce has a Grade 1 or mild Grade 2 injury, he could be back in a few weeks or less. Svech was the full outright tear. Snapped in two pieces, had to be sewn together and totally immobilized.
Ligaments are particularly fun things to injure. I had a fairly bad Grade 2 ankle sprain a couple years ago, and it took well over a year for that sucker to get back to normal. No surgery though, and no NHL docs.