The thought that immediately came to my mind was that the last thing the Twins need is another (and older version of) Kevin Correia, given my premise that the Twins need 3 starting pitchers better than Correia to compete. Arroyo's durability (pitched at least 199 innings every season after 2004, without ever visiting the Disabled List) and mentoring skills have been exalted, but he is thirty seven years old, with a 87 mph fastball and his numbers look so much like Kevin Correia's. How much? I went to look and confirm.
Here are Kevin Correia's and Bronson Arroyo's career numbers in several categories, from traditional like ERA to "advanced" like SIERA, FIP and xFIP:
Looking at the first five columns, ERA, FIP, xFIP, SIERA and K/9, it is immediately noticeable that one could not have picked any more similar pitchers. Also interesting is the fact that both their ERA are so close to their FIP, xFIP and SIERA. Other measurements not listed here, but are extremely alike are: career HR/FB (identical at 10.9), K% (15.3 for Arroyo and 15 for Correia), tERA (4.81 for Correia and 4.84 for Arroyo) and Hits per 9 IP (1.07 for Correia and 1.02 for Arroyo).
Alas. The data seem to indicate that my gut feeling was correct. They are the same pitcher. But with one (pretty large) difference in a single measurement: Their PE (pitching effectiveness) and xPE cannot be more different. You can read about PE and xPE (and why I like them as simple predictive measurements) starting here and following the relative links for more detail and how those measurements were developed. The difference (mainly walk rate differential-driven, which also reflects the changes in their WHIPs, since the hit rates are similar.) indicates that Arroyo is a much better pitcher and (unlike Correia whose numbers fall in the number 5 starter range with a PE of 7.92 and an xPE of 8.12) has been a solid number 3 type starter with a PE of 14.03 and an xPE of 13.60. But these are career numbers. How about his age 36, 2013 season? His PE of 17.52 and xPE of 16.13 in 2013 were even better than his total career numbers.
A couple of additional things that have to be mentioned:
a. Arroyo threw more than 100 pitches in 172 of his 385 games (44.7%) and 120 in 13 (3.4%). These numbers for other starting pitchers drafted when Arroyo did (1995): Ryan Dempster 52.9% and 7.5%, Jarrod Washburn 57.7% and 3.9%, Matt Morris 48.6% and 4%, Roy Halladay 57.9% and 4.8% and Russ Ortiz 53.8% and 12.8%. So if you are a pitch count believer, his arm has been abused less than his peers, which might indicate that there might be something in his 37 year old arm.
b. Arroyo is a different type of a pitcher. Here is an excellent writeup on Arroyo's stuff from yesterday by ESPN 1500's Twins' reporter Brandon Warne and here is a fangraphs interview where Arroyo describes his pitching style. A lot of very interesting things in that piece about his approach of the game, but his admission that hard throwing pitchers have an easier time dealing with batters is golden, because I have heard the argument (which I oppose dearly) that increased velocity does not make someone a better pitcher. Hearing it from an actual MLB veteran pitcher, is refreshing. Arroyo also admits that he sees himself pitching up to 3 more years.
So, suddenly and after a bit of research, I feel a bit better about this. My gut reaction was wrong: Arroyo is better than Correia and is expected to be better than Correia in the near future. So he can be one of the 3 pitchers better than Correia the Twins need. If the Twins get Arroyo they need 2 more pitchers better than him, hopefully top of the rotation types. On the other hand, he is thirty seven and I just hope that the elderly Floridian with the funky leg kick, who once was traded for Willy Mo Pena (by Twins' special assistant to the GM Wayne Krivsky nevertheless), remains healthy.