From the perspective of I like to learn something every day, and I had not the faintest idea about this, I found this link that explains it in terms simple enough for me to understand:
http://www.bible-teaching-about.com/evangelicalandpentecostal.html
I think the author is ill-informed. Emphasizing or downplaying "tongues" or miracles cannot make someone more or less evangelical. The author doesn't seem to understand the term, or why it came into use.
By evangelical what people in the United States generally mean refers to those Christians who believe in the essentials of the historic Christian Faith. That would be things such as the inerrancy and authority of the Bible (which is probably the most important), Diety and virgin birth of Jesus Christ along with His death, burial and resurrection, ascension to heaven, and His return. They believe in salvation by faith, the resurrection of the Christian’s body, and the reality of Satan, angels, heaven and hell.
What she's describing here is really a "Christian," although Catholic Christians might differ somewhat on "salvation by faith." "Fundamentalist" or "conservative" would also be a better term for what she's describing.
The term "Evangelical" makes sense, if you think of Evangelicals as putting a greater emphasis on the individual believer, and his relationship to God; and less emphasis on the believer as a member of a church, whose relationship to God is heavily dependent on the formal, corporate worship and life of the church.
I'm going to make some overly simplistic statements, to show the contrast between Evangelicals and more traditional groups, hopefully explaining what "Evangelicalism" came to mean.
Traditionally, historically, Catholics and some Protestant groups "evangelized" by baptizing infants, catechizing young children, and then through confirmation, first communion, and other rites by which individual believers were taught faith by the regular worship and rituals of the church. The Evangelical groups that came to the fore during the "Great Awakening" and similar movements, differed by emphasizing (you guessed it) evangelism. That is, preaching about the need for repentance, and forgiveness of sins through faith in Jesus. Or through small-group meetings (the early Methodists), and one-on-one discussions. Their emphasis was on the individual finding faith in God as an individual; not by simply following along with the rituals of the church.
As I said, the above is oversimplified. To under-simplify, Evangelical churches still catechize(d) children, and Catholics also preach(ed) about repentance and faith in Christ. Evangelicalism doesn't mean that church is unimportant, nor am I saying that Catholicism or conservative Lutheranism is just about being a faceless cog in the machinery of the church. But there is a difference in emphasis. Evangelicalism is marked by a greater emphasis on you - yes, you there - having a personal relationship with Christ. Non-evangelical Christianity puts greater emphasis on the institution.
I should add, "Evangelicalism" is only a buzz-word today because it is such a big chunk of American Christianity. It includes nearly every church that isn't Catholic, Lutheran, Orthodox, Anglican, or a few others; not to mention some churches in the aforementioned groups.
I should also add, though I'm excluding Lutherans, "Evangelical" was a term used to describe the early Lutherans. That's a different sense of the word, though.
