Tim Tebow -- Debut Was LEGITIMATELY Impressive ... Says Current MLB Slugger (VIDEO)

Tim Tebow's pro baseball debut was no joke -- the pitchers he was facing are the real deal and the fact he smacked a HR is very impressive ... so says Cleveland Indians outfielder Marlon Byrd.

FYI, Byrd has been in the big leagues since 2002 and knows all about the talent in the instructional league -- where Tebow hit a home run in his first at-bat earlier this week.

Byrd explains exactly why people need to show Tebow a little more respect for his first outing -- and says he thinks the NY Mets prospect has a real shot at getting to the big show.